scsi: core: Simplify control flow in scmd_eh_abort_handler()

Simplify the nested conditionals in the function by using a label for the
error path.  Introduce local "shost" to avoid repeated "sdev->shost" usage.
Also remove scsi_eh_complete_abort() since there is now only one place it
would be called.

Link: https://lore.kernel.org/r/20211029194311.17504-3-emilne@redhat.com


Signed-off-by: Ewan D. Milne <emilne@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>