qtnfmac: add support for STA HE rates

Add HE rates into STA info. Report HE Rx/Tx MCS if STA supports them.

Signed-off-by: Sergey Matyukevich <sergey.matyukevich.os@quantenna.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>