qcacmn: Clean up the extscan unified WMI (phase 3)

For a full explanation of the problem and phased solution refer to
"qcacmn: Clean up the extscan unified WMI (phase 1)", Change-Id
I11800361b572331cfada00fb7d518c314df20b43, in the qca-wifi-host-cmn
project.

For phase 3 (this change):
Remove the unions introduced in phase 1, leaving just the properly
named replacement identifiers.

Change-Id: Ia14a42a1a767a850fbfd82a5755ddea51246a95d
CRs-Fixed: 2282843
1 file changed