qcacmn: Fix Supported rates max length
Currently the driver checks for the supported rates IE,
and if the length of the IE is greater than 8, the driver
rejects the IE, according to spec.
But some APs supports 12 rates hence are not scanned.
Fix is to have a supported rates IE length check of 12 instead
of 8.
Change-Id: I3e32171e1b089ccc8754872fa5c37ba35b8b2cf7
CRs-Fixed: 3036878