Starting from kernel version 3.15, the crc32c module was renamed to
crc32c_generic.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@43291 3c298f89-4303-0410-b956-a3cf2f4a3e73