net: wirelss: bcmdhd  fixed disconnect issue for connecting status

Sometimes Framework issues connect and disconnect rapidly and continuously
with different APs.  In this case, the timing gap between connect and
disconnect is less than 20ms.  For this scenario, FW doesn't do anything
when DHD executes dissasoc while state of FW is associating status.  In
order to cancel current assoc procedure correctly, we need to call
scan_abort function, not DISASSOC.  FW will clean up ongoing assoc
procedure if FW is associating status.

b/18470879 Device stop responding after conducting rapid fire testing
           for making connection

Change-Id: If5c3ecb0ce4cc6a08aabf0e6ff19a16b22b33a95