ath9k_hw: remove ATH_BTCOEX_CFG_MCI

AR9462 uses modified version of 3-Wire hw scheme for btcoex.
MCI itself is not a separate hw scheme but it aids to manage
multiple bt profiles. In ar9462, bt priority traffic is identified
by the number of bt profile types instead of gpio. So that this
patch removes MCI hw scheme.

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