qcacld-3.0: Send roam scan offload config after roam sync complete

When host driver receives roam sync complete event, the
disable_hi_rssi to false if band is 2G and the high rssi
threshold delta needs to be sent to the firmware to take effect.
But presently the csr_roam_scan_offload exits with failure as
the driver issues start again.

Call csr_roam_scan_offload with ROAM_SCAN_OFFLOAD_UPDATE_CFG
command.

Change-Id: Ic3c9a729c290accbe9822948bc2363154db4c83f
CRs-Fixed: 2355359