Disable TX_STBC for both HT and VHT if the devices tx chainmask is '1'
TX_STBC is required only for devices with tx_chainmask > 1. This fixes
a ping failure for QCA9887 (1x1) in HT/VHT mode
Signed-off-by: NMohammed Shafi Shajakhan <mohammed@qti.qualcomm.com>
Signed-off-by: NKalle Valo <kvalo@qca.qualcomm.com>