brcm47xx: disable Linksys E1000 v1 by default

Disable the Linksys E1000 v1 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>

target/linux/brcm47xx/image/Makefile

@@ -715,6 +715,7 @@ define Device/linksys-e1000
   $(Device/linksys)
   DEVICE_ID := E100
   VERSION := 1.1.3
+  DEFAULT := n
 endef
 TARGET_DEVICES += linksys-e1000