[SCSI] ibmvfc: Send cancel when link is down

If attempting to abort requests due to a fail fail timeout
or error handling while the link is down, we cannot send
an abort out on the fabric. We can, however, send a cancel
to the VIOS. This fixes ibmvfc to send a cancel in this
case to prevent error handling from failing and/or
escalating.

Signed-off-by: Brian King <brking@linux.vnet.ibm.com>
Acked-by: Robert Jennings <rcj@linux.vnet.ibm.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>