usb: mtu3: make USB_MTU3_DUAL_ROLE depend on EXTCON but not USB_MTU3

In fact the driver depends on EXTCON only when it's configed as
USB_MTU3_DUAL_ROLE, so make USB_MTU3_DUAL_ROLE depend on EXTCON but
not USB_MTU3.
Signed-off-by: NChunfeng Yun <chunfeng.yun@mediatek.com>
Signed-off-by: NFelipe Balbi <felipe.balbi@linux.intel.com>

drivers/usb/mtu3/Kconfig

@@ -2,7 +2,7 @@
 
 config USB_MTU3
 	tristate "MediaTek USB3 Dual Role controller"
-	depends on EXTCON && (USB || USB_GADGET) && HAS_DMA
+	depends on (USB || USB_GADGET) && HAS_DMA
 	depends on ARCH_MEDIATEK || COMPILE_TEST
 	select USB_XHCI_MTK if USB_SUPPORT && USB_XHCI_HCD
 	help
@@ -40,6 +40,7 @@ config USB_MTU3_GADGET
 config USB_MTU3_DUAL_ROLE
 	bool "Dual Role mode"
 	depends on ((USB=y || USB=USB_MTU3) && (USB_GADGET=y || USB_GADGET=USB_MTU3))
+	depends on (EXTCON=y || EXTCON=USB_MTU3)
 	help
 	  This is the default mode of working of MTU3 controller where
 	  both host and gadget features are enabled.