ath9k: Tune ANI function processing on AP mode during ANI reset

For AP mode we must tune ANI specially for 2 GHz and
for 5 GHz. We mask in only the flags we want to toggle
on ath9k_hw_ani_control() through the ah->ani_function
bitmask, this will take care of ignoring changes during
ANI reset which we were disabling before.

Testedy-by: Steven Luo <steven@steven676.net>
Cc: Bennyam Malavazi <bennyam.malavazi@atheros.com>
Cc: Jouni Malinen <jouni.malinen@Atheros.com>
Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>