keep default as 3.14, mt7621 gic need to be ported to 3.18

Signed-off-by: John Crispin <blogic@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@44349 3c298f89-4303-0410-b956-a3cf2f4a3e73