ath9k: Fix AR9285 specific noise floor eeprom reads.

Fix AR9285 specific noise floor reads and initialize tx and rx
chainmask during reset. This along with the following earlier
patches of ath9k fixes an issue with association noticed in
noisy environment.

ath9k: Fix typo in chip version check
ath9k: Remove unnecessary gpio configuration in ath9k_hw_reset()
ath9k: Fix bug in NF calibration

Signed-off-by: Senthil Balasubramanian <senthilkumar@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>