mfd: omap-usb-host: Mark expected switch fall-throughs

Mark switch cases where we are expecting to fall through.

This patch fixes the following warnings:

drivers/mfd/omap-usb-host.c: In function 'usbhs_runtime_resume':
drivers/mfd/omap-usb-host.c:303:7: warning: this statement may fall through [-Wimplicit-fallthrough=]
if (!IS_ERR(omap->hsic480m_clk[i])) {
^
drivers/mfd/omap-usb-host.c:313:3: note: here
case OMAP_EHCI_PORT_MODE_TLL:
^~~~
drivers/mfd/omap-usb-host.c: In function 'usbhs_runtime_suspend':
drivers/mfd/omap-usb-host.c:345:7: warning: this statement may fall through [-Wimplicit-fallthrough=]
if (!IS_ERR(omap->hsic480m_clk[i]))
^
drivers/mfd/omap-usb-host.c:349:3: note: here
case OMAP_EHCI_PORT_MODE_TLL:
^~~~

Reported-by: Stephen Rothwell <[e-mail]>
Signed-off-by: Gustavo A. R. Silva <[e-mail]>
Reviewed-by: Kees Cook <[e-mail]>
Signed-off-by: Lee Jones <[e-mail]>

drivers/mfd/omap-usb-host.c

···
 					 i, r);
 				}
 			}
-		/* Fall through as HSIC mode needs utmi_clk */
+		/* Fall through - as HSIC mode needs utmi_clk */
 
 		case OMAP_EHCI_PORT_MODE_TLL:
 			if (!IS_ERR(omap->utmi_clk[i])) {
···
 
 			if (!IS_ERR(omap->hsic480m_clk[i]))
 				clk_disable_unprepare(omap->hsic480m_clk[i]);
-		/* Fall through as utmi_clks were used in HSIC mode */
+		/* Fall through - as utmi_clks were used in HSIC mode */
 
 		case OMAP_EHCI_PORT_MODE_TLL:
 			if (!IS_ERR(omap->utmi_clk[i]))