wcn36xx: Set feature DOT11AC for wcn3680

In order for the firmware to process extended V1 parameters with the
addtional VHT fields added we need to first enable the feature bit DOT11AC.
Once done the version number in the HAL message header will be acted upon
by the firmware.

Extended V1 parameters are a prerequisite for 802.11ac speeds since we
cannot communicate VHT parameters to the firmware absent the extended data
structures.

Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20200829033846.2167619-11-bryan.odonoghue@linaro.org