scsi: Do not set cmd_per_lun to 1 in the host template

'0' is now used as the default cmd_per_lun value,
so there's no need to explicitly set it to '1' in the
host template.

Signed-off-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: James Bottomley <JBottomley@Odin.com>