ath9k_hw: Support fast channel change on 5GHz for AR9003 chips

The commit "ath9k_hw: Improve fast channel change for AR9003 chips"
fixes the fast channel change issue for AR9003 chips that was
originally observed in AR9382 chip. Hence enabling fastcc support
again for 11A channel for AR9003 chips.

Cc: Paul Stewart <pstew@google.com>
Signed-off-by: Rajkumar Manoharan <rmanohar@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>