[SCSI] ibmvfc: Improve device rediscovery

For certain scenarios during device rediscovery, we detect we need
to log back into a target. Currently we do just that - PLOGI/PRLI
back into the target. Change the code to delete and add the target
from the FC transport layer as well, to ensure we handle any cases
where the target may have changed.

Signed-off-by: Brian King <brking@linux.vnet.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>