qcacld-3.0: Add check to avoid potential OOB access for bssid_list

In wma_group_num_bss_to_scan_id(), bssid_list may be accessed out
of boundary.

Add check to avoid potential OOB access for bssid_list.

Change-Id: I218af0fe617f64a50c7c296c622f7fac01e1b4fc
CRs-Fixed: 3357461