[SCSI] SCSI core: Allow QUIESCE -> CANCEL sdev transition

We have to be able to remove SCSI devices even when they are suspended, so
QUIESCE -> CANCEL must be a legal state transition.  This patch (as727)
adds the transition to the state machine.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>