usb: phy: ab8500-usb: Mark expected switch fall-throughs

Mark switch cases where we are expecting to fall through.

This patch fixes the following warnings:

drivers/usb/phy/phy-ab8500-usb.c: In function 'ab8500_usb_link_status_update':
drivers/usb/phy/phy-ab8500-usb.c:424:9: warning: this statement may fall through [-Wimplicit-fallthrough=]
   event = UX500_MUSB_RIDB;
   ~~~~~~^~~~~~~~~~~~~~~~~
drivers/usb/phy/phy-ab8500-usb.c:425:2: note: here
  case USB_LINK_NOT_CONFIGURED_8500:
  ^~~~
drivers/usb/phy/phy-ab8500-usb.c:440:9: warning: this statement may fall through [-Wimplicit-fallthrough=]
   event = UX500_MUSB_RIDC;
   ~~~~~~^~~~~~~~~~~~~~~~~
drivers/usb/phy/phy-ab8500-usb.c:441:2: note: here
  case USB_LINK_STD_HOST_NC_8500:
  ^~~~
drivers/usb/phy/phy-ab8500-usb.c:459:9: warning: this statement may fall through [-Wimplicit-fallthrough=]
   event = UX500_MUSB_RIDA;
   ~~~~~~^~~~~~~~~~~~~~~~~
drivers/usb/phy/phy-ab8500-usb.c:460:2: note: here
  case USB_LINK_HM_IDGND_8500:
  ^~~~
drivers/usb/phy/phy-ab8500-usb.c: In function 'ab8505_usb_link_status_update':
drivers/usb/phy/phy-ab8500-usb.c:332:9: warning: this statement may fall through [-Wimplicit-fallthrough=]
   event = UX500_MUSB_RIDB;
   ~~~~~~^~~~~~~~~~~~~~~~~
drivers/usb/phy/phy-ab8500-usb.c:333:2: note: here
  case USB_LINK_NOT_CONFIGURED_8505:
  ^~~~
drivers/usb/phy/phy-ab8500-usb.c:352:9: warning: this statement may fall through [-Wimplicit-fallthrough=]
   event = UX500_MUSB_RIDC;
   ~~~~~~^~~~~~~~~~~~~~~~~
drivers/usb/phy/phy-ab8500-usb.c:353:2: note: here
  case USB_LINK_STD_HOST_NC_8505:
  ^~~~
drivers/usb/phy/phy-ab8500-usb.c:370:9: warning: this statement may fall through [-Wimplicit-fallthrough=]
   event = UX500_MUSB_RIDA;
   ~~~~~~^~~~~~~~~~~~~~~~~
drivers/usb/phy/phy-ab8500-usb.c:371:2: note: here
  case USB_LINK_HM_IDGND_8505:
  ^~~~

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20190729000631.GA24165@embeddedor
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/phy/phy-ab8500-usb.c

@@ -330,6 +330,7 @@ static int ab8505_usb_link_status_update(struct ab8500_usb *ab,
 	switch (lsts) {
 	case USB_LINK_ACA_RID_B_8505:
 		event = UX500_MUSB_RIDB;
+		/* Fall through */
 	case USB_LINK_NOT_CONFIGURED_8505:
 	case USB_LINK_RESERVED0_8505:
 	case USB_LINK_RESERVED1_8505:
@@ -350,6 +351,7 @@ static int ab8505_usb_link_status_update(struct ab8500_usb *ab,
 
 	case USB_LINK_ACA_RID_C_NM_8505:
 		event = UX500_MUSB_RIDC;
+		/* Fall through */
 	case USB_LINK_STD_HOST_NC_8505:
 	case USB_LINK_STD_HOST_C_NS_8505:
 	case USB_LINK_STD_HOST_C_S_8505:
@@ -368,6 +370,7 @@ static int ab8505_usb_link_status_update(struct ab8500_usb *ab,
 	case USB_LINK_ACA_RID_A_8505:
 	case USB_LINK_ACA_DOCK_CHGR_8505:
 		event = UX500_MUSB_RIDA;
+		/* Fall through */
 	case USB_LINK_HM_IDGND_8505:
 		if (ab->mode == USB_IDLE) {
 			ab->mode = USB_HOST;
@@ -422,6 +425,7 @@ static int ab8500_usb_link_status_update(struct ab8500_usb *ab,
 	switch (lsts) {
 	case USB_LINK_ACA_RID_B_8500:
 		event = UX500_MUSB_RIDB;
+		/* Fall through */
 	case USB_LINK_NOT_CONFIGURED_8500:
 	case USB_LINK_NOT_VALID_LINK_8500:
 		ab->mode = USB_IDLE;
@@ -438,6 +442,7 @@ static int ab8500_usb_link_status_update(struct ab8500_usb *ab,
 	case USB_LINK_ACA_RID_C_HS_8500:
 	case USB_LINK_ACA_RID_C_HS_CHIRP_8500:
 		event = UX500_MUSB_RIDC;
+		/* Fall through */
 	case USB_LINK_STD_HOST_NC_8500:
 	case USB_LINK_STD_HOST_C_NS_8500:
 	case USB_LINK_STD_HOST_C_S_8500:
@@ -457,6 +462,7 @@ static int ab8500_usb_link_status_update(struct ab8500_usb *ab,
 
 	case USB_LINK_ACA_RID_A_8500:
 		event = UX500_MUSB_RIDA;
+		/* Fall through */
 	case USB_LINK_HM_IDGND_8500:
 		if (ab->mode == USB_IDLE) {
 			ab->mode = USB_HOST;