qcacld-3.0: Replace channel ID with channel frequency

Replace channel ID(channelId) with channel frequency(
chan_freq) in struct bss_description.

Add code for chan_freq's value population in the same
struct wherever channelId's value population occures.

Remove a few camel cases detected by checkpatch.

Change-Id: I84d193b67f642df310997865ec6e1b62e3518f98
CRs-Fixed: 2488826
7 files changed