usb: dwc3: fix Kconfig dependency to accept host driver in drivers/usb/dwc3

We see the choice of USB_DWC3_HOST / _GADGET in drivers/usb/dwc3/Kconfig,
but we can not choose USB_DWC3_HOST unless USB_GADGET is defined.
This is strange.

Loosen the "depends on" and also move "select USB_GADGET_DUALSPEED" to
the correct place.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

drivers/usb/dwc3/Kconfig

@@ -1,7 +1,6 @@
 config USB_DWC3
 	bool "DesignWare USB3 DRD Core Support"
-	depends on (USB && USB_GADGET)
-	select USB_GADGET_DUALSPEED
+	depends on USB_HOST || USB_GADGET
 	help
 	  Say Y here if your system has a Dual Role SuperSpeed
 	  USB controller based on the DesignWare USB3 IP Core.
@@ -21,6 +20,7 @@ config USB_DWC3_HOST
 config USB_DWC3_GADGET
 	bool "Gadget only mode"
 	depends on USB_GADGET
+	select USB_GADGET_DUALSPEED
 	help
 	  Select this when you want to use DWC3 in gadget mode only,
 	  thereby the host feature will be regressed.