ath9k: defer btcoex scheme update

As btcoex scheme updation might sleep, remove the function call
from tasklet context and queue it up as a separate work.

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

drivers/net/wireless/ath/ath9k/ath9k.h

@@ -698,6 +698,7 @@ struct ath_softc {
 #ifdef CONFIG_ATH9K_BTCOEX_SUPPORT
 	struct ath_btcoex btcoex;
 	struct ath_mci_coex mci_coex;
+	struct work_struct mci_work;
 #endif
 
 	struct ath_descdma txsdma;