ath10k: do not overwrite max_antenna_gain

Seems like we have an old bug, where we incidently overwrites
the max_antenna_gain we pass to firmware, with zero value.

End of all we are artifically reducing the output power.

This patch removes the excessive assignment on max_antenna_gain,
which is being provided by regulatory domain, and consequently
improves the tx power.

Signed-off-by: Marek Puzyniak <marek.puzyniak@tieto.com>
Signed-off-by: Bartosz Markowski <bartosz.markowski@tieto.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>
ath10k: allow the supported rate change by reassociate peer

IBSS mode requires the changing of supported rate. Do this
by reassociate the peer. The investigation shows that if move
from legacy to HT, the rate control won't work after changing
the supported rate. But once changing the supported rate to HT,
user can assign the TxRate in HT mode.

Signed-off-by: Chun-Yeow Yeoh <yeohchunyeow@gmail.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>