broadcom-wl: add default tx and rx antennas

This adds default tx and rx antennas, so that LuCI shows automatic as the default radio option for the antennas.

Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>

Backport of r42085

git-svn-id: svn://svn.openwrt.org/openwrt/branches/barrier_breaker@42350 3c298f89-4303-0410-b956-a3cf2f4a3e73

package/kernel/broadcom-wl/files/lib/wifi/broadcom.sh

@@ -450,7 +450,8 @@ detect_broadcom() {
 config wifi-device  wl${i}
 	option type     broadcom
 	option channel  ${channel:-11}
-
+	option txantenna 3
+	option rxantenna 3
 	# REMOVE THIS LINE TO ENABLE WIFI:
 	option disabled 1