qcacld-3.0: Introduce getband vendor command

Update calls from reg_get_curr_band to reg_get_band since
they provide the same functionality.
Update calls to reg_get_band to expect a bitmap since the API
has been updated.
Update getband driver command to convert the bitmap to the
old values. Also add the new vendor command getband.

Change-Id: I069489ebf4826f8f4bfcb974b74e4d0591d5b33f
CRs-fixed: 2726361
6 files changed