mwifiex: update domain_info upon band change in start_ap

It was observed that AP beacons would not reflect correct regulatory
information upon starting AP in A band. This was because of missing
AP config band update in set_channel of start_ap. Also we configure 11D
settings info FW only for specific band. So we need to download domain
info to FW even if domain remains unchanged but band is changed.

Signed-off-by: Avinash Patil <patila@marvell.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>