ath9k: enable ANI for ar9100 chips

  Enable ANI for ar9100 since it seems to be working fine (and as a
matter of fact ANI was always performed for ar9100 since code which
was supposed to disable it didn't achieve this goal).
  This patch sets config.enable_ani to default (true) value for
ar9100.

Signed-off-by: Nikolay Martynov <mar.kolya@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>