[kernel] fix video modules package generation

The folder layout changed between 3.6 and 3.7

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

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@34960 3c298f89-4303-0410-b956-a3cf2f4a3e73