Roam offload init command should be sent to firmware only
for STA mode. For P2P vdev, if roam init command is sent,
it causes abnormal target behavior.
Don't send roam init command if the vdev opmode is not
Station.
Change-Id: I0bfc3c6b4bc2eef7459b092101bc4d72c68761e5
CRs-Fixed: 2924563