kernel: disable the yaffs2 /proc code to make it compile on linux 3.10 (#13848)

Signed-off-by: Felix Fietkau <nbd@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt@37285 3c298f89-4303-0410-b956-a3cf2f4a3e73