If DBS 2x2 mode is supported, to operate in 2.4Ghz the driver needs to
be in DBS mode before vdev start/restart is sent on 2.4Ghz channel.
If STA is connected to a 5Ghz channel and the PEER AP switch from 5Ghz
to 2.4Ghz channel, it sends vdev restart without sending the HW mode
change to firmware.
Fix is to set HW mode before the initiating vdev restart if new channel
is 2.4Ghz and 2x2 DBS is supported and current HW mode is not DBS
Change-Id: I6dc57f37e155f0e29b17840e4e246de773f42b3e
CRs-Fixed: 2419642
bc4261fe8c