The band_capability field is used in other places to be
a bitmap over reg_wifi_band. Update the field in wma_tgt_cfg and
wlan_mlme_generic to take the same bitmap for consistency.
Update all references to these fields to expect a bitmap as well.
Change-Id: I8abd697e2fbe02b4eadd32f3027bef7408bac2a0
CRs-fixed: 2726710