usb: otg: mv_otg: Add dependence

This otg driver depends on marvell EHCI driver, so add the dependence.
It can fix the following build error on i386:

ERROR: "usb_remove_hcd" [drivers/usb/otg/mv_otg.ko] undefined!
ERROR: "usb_add_hcd" [drivers/usb/otg/mv_otg.ko] undefined!
Signed-off-by: Neil Zhang <zhangwm@marvell.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/otg/Kconfig

@@ -118,7 +118,7 @@ config FSL_USB2_OTG
 
 config USB_MV_OTG
 	tristate "Marvell USB OTG support"
-	depends on USB_MV_UDC && USB_SUSPEND
+	depends on USB_EHCI_MV && USB_MV_UDC && USB_SUSPEND
 	select USB_OTG
 	select USB_OTG_UTILS
 	help