ath9k: Remove RTT/MCI code from SoC calibration

RTT is enabled only for AR9462 and MCI for AR9462/AR9565.
Also, manual peak calibration is not done for any of the
SoC chips.

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