brcm47xx: disable Netgear WNR2000 v2 by default

Disable the Netgear WNR2000 v2 image by default as the device has
insufficient flash space for release build images.

Ref: https://forum.openwrt.org/t/devices-too-big-to-save-overlay/18161/72
Signed-off-by: Jo-Philipp Wich <jo@mein.io>
[drop change on netgear-wnr3500l-v1-na]
Signed-off-by: Adrian Schmutzler <freifunk@adrianschmutzler.de>

target/linux/brcm47xx/image/Makefile

@@ -916,6 +916,7 @@ define Device/netgear-wnr2000v2
   $(Device/netgear)
   NETGEAR_BOARD_ID := U12H114T00_NETGEAR
   NETGEAR_REGION := 2
+  DEFAULT := n
 endef
 TARGET_DEVICES += netgear-wnr2000v2