qtnfmac: advertise support of inactivity timeout

Wireless device may implement a logic to kick-out STA due to inactivity
for a certain period of time. This feature needs to be advertised to
higher layers if supported. Timeout value is still taken from
parameters to START_AP command, nothing changes here.

Signed-off-by: Igor Mitsyanko <igor.mitsyanko.os@quantenna.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>