ath9k_hw: add HTC init hardware call for special resets for AR9271

AR9271 needs a full reset only upon the first reset, add
a call for the driver to enable these special resets. We
can optimize this out later without an export.

Signed-off-by: Sujith <Sujith.Manoharan@atheros.com>
Signed-off-by: Vasanthakumar Thiagarajan <vasanth@atheros.com>
Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>