qcacld-3.0: Update MCS index appropriately
qcacld-2.0 to qcacld-3.0 propagation
When AP is configured with MCS index less than 4(43Mbps) then Host
reports invalid MCS Index to upper-layer, leading to display invalid
link speed on GUI.
Updating MCS index with valid value and thereby updating correct MCS
index to upper-layer
Change-Id: Ibd1503be3825c879b7fa52bdfb6ff07423c39023
CRs-Fixed: 855022