umbim: move package to 'WWAN' submenu

'uqmi' was moved to 'WWAN' submenu in 9abdeee.
Let's be consistent and do the same with 'umbim'.

Signed-off-by: Piotr Dymacz <pepe2k@gmail.com>

package/network/utils/umbim/Makefile

@@ -23,6 +23,7 @@ include $(INCLUDE_DIR)/cmake.mk
 define Package/umbim
   SECTION:=net
   CATEGORY:=Network
+  SUBMENU:=WWAN
   DEPENDS:=+libubox +kmod-usb-net +kmod-usb-net-cdc-mbim +wwan
   TITLE:=Control utility for mobile broadband modems
 endef