ath9k: Remove unneeded variable to store return value

ath9k_reg_rmw_single do not need return value to cope with different
cases. And change functon return type to void.

Signed-off-by: zhong jiang <zhongjiang@huawei.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
1 file changed