qcacld-3.0: Synchronize sta_info access in host driver

Currently there is no synchronized access for sta_info. Because of this
memory use after free is getting triggered.

To resolve this, use a reference count for sta_info to check whether it
is in use or not before freeing.

Change-Id: I696461a1f53f4cc4739963f3f97ada31d3fa15f3
CRs-Fixed: 2637074
7 files changed