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>

target/linux/ramips/image/rt305x.mk

@@ -1187,7 +1187,8 @@ define Device/zyxel_keenetic
   IMAGE_SIZE := 7872k
   DEVICE_VENDOR := ZyXEL
   DEVICE_MODEL := Keenetic
-  DEVICE_PACKAGES := kmod-usb2 kmod-usb-ehci kmod-usb-ledtrig-usbport
+  DEVICE_PACKAGES := kmod-usb2 kmod-usb-ehci kmod-usb-ledtrig-usbport \
+	kmod-usb-dwc2
   SUPPORTED_DEVICES += kn
 endef
 TARGET_DEVICES += zyxel_keenetic