ath9k: fix a misprint which leads to incorrect calibration

This patch addresses an issue with incorrect HW register
AR_PHY_TX_IQCAL_CORR_COEFF_B1 definition which leads to incorrect clibration.

Cc: stable@kernel.org
Signed-off-by: Alex Hacker <hacker@epn.ru>
Signed-off-by: John W. Linville <linville@tuxdriver.com>