ath9k: ath9k_hw_4k_set_board_values: use rmw buffer
ath9k: ath9k_hw_4k_set_board_values: use rmw buffer

it will reduce exution time from 14ms to 2ms on ar9271

Signed-off-by: Oleksij Rempel <ba324ca7b1c77fc20bb970d5aff6eea9377918a5@rempel-privat.de>
Signed-off-by: Kalle Valo <7081a7d99b8c74c0698a728df19e3915a995d7e1@codeaurora.org>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs