qcacmn: Fix possible out of bound access

In reg_set_5g_channel_params if the input channel bandwidth
is 5MHz then while getting the next lower bandwidth out of
bound access occurs.
Fix out of bound access in getting next lower bandwidth value.

Change-Id: I309909661f0357d482387e92353024400a042295
CRs-Fixed: 2525496
1 file changed