qcacld-3.0: Convert SME code legacy channel ID usage

Modify the following 2 APIs' code and parameters to use frequency
instead of channel ID:
   sme_get_roam_scan_channel_list
   drv_cmd_get_roam_scan_channels

Change-Id: I4e6edee71ef25bf73c170813159f5078f0c3e612
CRs-Fixed: 2554148
3 files changed