[SCSI] scsi_scan: add missing interim SDEV_DEL state if slave_alloc fails

We were running i/o and performing a bunch of hba resets in a loop.
This forces a lot of target removes and then rescans. Since the
resets are occuring during scan it's causing the scan i/o to timeout,
invoking error recovery, etc.  We end up getting some nasty crashing
in scsi_scan.c due to references to old sdevs that are failing
but had some lingering references that kept them around.

Fix by setting device state to SDEV_DEL if the LLD's slave_alloc
fails.

Signed-off-by: James Smart <james.smart@emulex.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>