qcacld-3.0: Fix incorrect channel width downgrade

After the connection is established with HE160/VHT160 AP,
the STA downgrades the channel width to VHT80/HE80, leading
to 50% TPUT reduction.

The associated beacon processing doesn't consider the new VHT OP
IE definition while parsing the channel width. Fix the channel
width processing in the beacon processing.

Change-Id: Icd7d36a8352be7574474fb5f37fa9b4ca291aa04
CRs-Fixed: 3211833