ath10k: fix rts profile for second rate series

By default rts protection is enabled in firmware for the second
rateset. Currently ath10k selects RTS profile (only for software
retries), when legacy stations are associated or asked by mac80211.
On congested environment, when AP is running in HT/VHT mode and
there are no legacy clients associated, this will impact the
robustness. Also enabling RTS protection only for second rateset will
not impact performance on clear environment. Fix that.

Signed-off-by: Rajkumar Manoharan <rmanohar@qti.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>