qcacld-3.0: Enable roaming based on conn status in case of STA + STA

In case of STA + STA, If first STA (say STA1) is in connected state
and second STA (say STA2) has multiple candidate APs for connection,
STA2 tries connection with each APs one by one till either
successful a connection or no AP left to initiate connection.

Currently, If STA2 initiate connection with first candidate, and if
it fails, STA2 enables roaming on other interfaces (here STA1)
irrespective of connection status. This results, after connection
failure of STA2 with first AP, STA1 gets permission to start roaming.
So there could be a possibility that STA1 started roaming on VDEV0
and STA2 started connection with next AP on VDEV1 which results in
two VDEV start/re-start at the same time in FW.

Fix is to allow roaming on other interfaces only after if association
is successful or all possible candidates APs are tried by current
interface.

Change-Id: I5b765d5a8ffc10ad2903d746537e41501890ca8b
CRs-Fixed: 2577368