ath9k: Fix sparse warnings

drivers/net/wireless/ath/ath9k/init.c:199:21: warning: context imbalance
in 'ath9k_reg_rmw' - different lock contexts for basic block
drivers/net/wireless/ath/ath9k/xmit.c:1175:31: warning: context
imbalance in 'ath_drain_txq_list' - unexpected unlock
drivers/net/wireless/ath/ath9k/xmit.c:2047:23: warning: context
imbalance in 'ath_tx_process_buffer' - unexpected unlock
drivers/net/wireless/ath/ath9k/ar9003_eeprom.c:3041:24: warning: cast to
restricted __le32

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