The wl1271 firmware supports maximun 25.5dBm, so the driver was returning
-EINVALID to anything above that. This patch uses the channel max_power
option to limit the TX power to 25dBm.
Signed-off-by: Luciano Coelho <luciano.coelho@nokia.com> Reviewed-by: Juuso Oikarinen <juuso.oikarinen@nokia.com> Signed-off-by: John W. Linville <linville@tuxdriver.com>