ath9k: fix radar parameters initialization

Move ath9k_hw_set_radar_params() in ath9k_hw_reset() in order to avoid
AR_PHY_RADAR registers are overwritten after hw reset

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