usb: dwc3: meson-g12a: Don't use ret uninitialized in dwc3_meson_g12a_otg_init

Clang warns:

../drivers/usb/dwc3/dwc3-meson-g12a.c:421:6: warning: variable 'ret' is
used uninitialized whenever 'if' condition is false
[-Wsometimes-uninitialized]
        if (priv->otg_mode == USB_DR_MODE_OTG) {
            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../drivers/usb/dwc3/dwc3-meson-g12a.c:455:9: note: uninitialized use
occurs here
        return ret;
               ^~~
../drivers/usb/dwc3/dwc3-meson-g12a.c:421:2: note: remove the 'if' if
its condition is always true
        if (priv->otg_mode == USB_DR_MODE_OTG) {
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../drivers/usb/dwc3/dwc3-meson-g12a.c:415:9: note: initialize the
variable 'ret' to silence this warning
        int ret, irq;
               ^
                = 0
1 warning generated.

It is not wrong, ret is only used when that if statement is true. Just
directly return 0 at the end to avoid this.

Fixes: 729149c53f04 ("usb: dwc3: Add Amlogic A1 DWC3 glue")
Reported-by: kbuild test robot <lkp@intel.com>
Link: https://groups.google.com/d/msg/clang-built-linux/w5iBENco_m4/PPuXreAxBQAJ
Link: https://github.com/ClangBuiltLinux/linux/issues/869
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Felipe Balbi <balbi@kernel.org>

drivers/usb/dwc3/dwc3-meson-g12a.c

@@ -452,7 +452,7 @@ static int dwc3_meson_g12a_otg_init(struct platform_device *pdev,
 	if (IS_ERR(priv->role_switch))
 		dev_warn(dev, "Unable to register Role Switch\n");
 
-	return ret;
+	return 0;
 }
 
 static int dwc3_meson_g12a_probe(struct platform_device *pdev)