lantiq: ubinize autoresize flag for rootfs_data

Setting this flag allows rootfs_data to expand on first boot
to fill remaining free space on nand.

Signed-off-by: Ben Mulvihill <ben.mulvihill@gmail.com>

SVN-Revision: 41310

target/linux/lantiq/image/ubinize-overlay.cfg

@@ -19,3 +19,5 @@ vol_type=dynamic
 # Volume name
 vol_name=rootfs_data
 vol_size=1MiB
+# Autoresize volume at first mount
+vol_flags=autoresize