ath79: ubnt-xm: disable WAN on (rocket|bullet)-m

ubnt,bullet-m and ubnt,rocket-m targets support only single Ethernet
port, therefore disable creation of WAN zone and interfaces for them,
as their intended purpose is a wireless bridge. This aligns the
configuration with one found in ar71xx target.

ubnt,nano-m target is kept as is, being a two-port device.

Signed-off-by: Lech Perczak <lech.perczak@gmail.com>

target/linux/ath79/base-files/etc/board.d/02_network

@@ -19,6 +19,8 @@ ath79_setup_interfaces()
 	tplink,tl-mr3020-v1|\
 	tplink,tl-mr3040-v2|\
 	tplink,tl-wr703n|\
+	ubnt,bullet-m|\
+	ubnt,rocket-m|\
 	ubnt,unifiac-lite|\
 	ubnt,unifiac-mesh|\
 	ubnt,unifi)