atheros: remove useless get_c0_compare_int fix

Remove get_c0_compare_int fix which is useless for latest kernels.

Tested on Ubnt Bullet2, which could successfully boot without this
workaround.

Signed-off-by: Sergey Ryazanov <ryazanov.s.a@gmail.com>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@40593 3c298f89-4303-0410-b956-a3cf2f4a3e73