In case prefer 5 GHz preference is set, move the 5GHz channels ahead
of 2GHz channels in channel list as used in Early Stop Roaming Scan
feature. This ensures that while roaming, when these features are
enabled DUT will scan 5 GHz channels first and roam if a candidate
AP is found.
Change-Id: I96d997560a3eca5fd378aa3ed78c5766d097cafd
CRs-Fixed: 951959