scsi: core: Remove scsi_init_cmd_errh

There is no good reason to keep this functionality as a separate function,
just merge it into the only caller.

Link: https://lore.kernel.org/r/20201005084130.143273-3-hch@lst.de


Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>