ath9k: fix 5/10MHz channel width initialization on ar9003

Move ath9k_hw_set_rfmode() after ath9k_hw_process_ini() in order to avoid
AR_PHY_MODE register is overwritten with default values by
ar9003_hw_process_ini()

Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi83@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>