ath9k: Remove ATH9K_HW_CAP_MCI checks

With the ability to remove BTCOEX support at compile time,
these checks are no longer needed.

Signed-off-by: Sujith Manoharan <c_manoha@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>