qcacld-3.0: Fix peer unmap failure due to invalid roam scan mode value

When supplicant disables firmware roam, RSO stop command with
roam scan mode value 4 is sent to firmware and this value 4
indicates the firmare to enable only Forced roam trigger(roam
invoke command from host). But before
ROAM_DEINIT(WMI_VDEV_PARAM_ROAM_FW_OFFLOAD with value zero) is
posted to firmware, the roam scan mode should be 0 or else there
could be potential peer unmap failures if firmware has already
started roam and disconnect is triggered from north bound or from
peer.

To avoid this, in the roam offload state machine handle the state
switch from RSO stopped to deinit if supplicant disabled roaming
flag is set and send RSO stop with roam scan mode value 0 to
firmware.

Change-Id: If50a306b6019320ddab2ac1695a57718d27f477a
CRs-Fixed: 2755948