ramips: add kmod-usb-dwc2 to ZyXEL Keenetic image

ZyXEL Keenetic has a USB port. Thus, DWC2 USB controller driver should
be in the default image for this device.

Fixes: a7cbf59e0e ("ramips: add new device ZyXEL Keenetic as kn")
Signed-off-by: Alexey Dobrovolsky <dobrovolskiy.alexey@gmail.com>
[fixed whitespace issue]
Signed-off-by: Petr Štetiar <ynezz@true.cz>
(backported from commit 0a182fcba6d9cb2cf74cae9114ea4770ef928f75)
Signed-off-by: Adrian Schmutzler <freifunk@adrianschmutzler.de>

target/linux/ramips/image/rt305x.mk

@@ -906,7 +906,8 @@ define Device/kn
   BLOCKSIZE := 64k
   IMAGE_SIZE := 7872k
   DEVICE_TITLE := ZyXEL Keenetic
-  DEVICE_PACKAGES := kmod-usb-core kmod-usb2 kmod-usb-ehci kmod-usb-ledtrig-usbport
+  DEVICE_PACKAGES := kmod-usb-core kmod-usb2 kmod-usb-ehci \
+	kmod-usb-ledtrig-usbport kmod-usb-dwc2
 endef
 TARGET_DEVICES += kn