ath9k: Remove dead code in rate control

ath9k rate control is based on only PER (packet error rate),
remove unused code which was intented to do rssi based rate
selection.

Signed-off-by: Vasanthakumar Thiagarajan <vasanth@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
1 file changed