scsi: ufs: Don't attempt to suspend if the hba is not powered

If the UFS device is not present the host is powered off but during
suspend/resume operations it is possible to communicate with the
hba which is already powered off. Fix this by not attempting to
suspend in case hba is already powered off.

Change-Id: I99ed886d9158dc54fcb7331c70c3d046f458ae66
Signed-off-by: Sujit Reddy Thumma <sthumma@codeaurora.org>