usb: musb: omap2430: Get rid of musb .set_vbus for omap2430 glue

We currently have musb_set_vbus() called from two different paths. Mostly
it gets called from the USB PHY via omap_musb_set_mailbox(), but in some
cases it can get also called from musb_stage0_irq() rather via .set_vbus:

(musb_set_host [musb_hdrc])
(omap2430_musb_set_vbus [omap2430])
(musb_stage0_irq [musb_hdrc])
(musb_interrupt [musb_hdrc])
(omap2430_musb_interrupt [omap2430])

This is racy and will not work with introducing generic helper functions
for musb_set_host() and musb_set_peripheral(). We want to get rid of the
busy loops in favor of usleep_range().

Let's just get rid of .set_vbus for omap2430 glue layer and let the PHY
code handle VBUS with musb_set_vbus(). Note that in the follow-up patch
we can completely remove omap2430_musb_set_vbus(), but let's do it in a
separate patch as this change may actually turn out to be needed as a
fix.

Reported-by: Pavel Machek <pavel@ucw.cz>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Bin Liu <b-liu@ti.com>
Link: https://lore.kernel.org/r/20200115132547.364-5-b-liu@ti.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/musb/omap2430.c

@@ -361,8 +361,6 @@ static const struct musb_platform_ops omap2430_ops = {
 	.init		= omap2430_musb_init,
 	.exit		= omap2430_musb_exit,
 
-	.set_vbus	= omap2430_musb_set_vbus,
-
 	.enable		= omap2430_musb_enable,
 	.disable	= omap2430_musb_disable,