scsi: use short driver name for per-driver cmd slab caches

hostt->name might contain space, so use the ->proc_name short name instead
when creating per-driver command slabs.

Signed-off-by: James Bottomley <JBottomley@Parallels.com>
Reported-by: poma <pomidorabelisima@gmail.com>
Tested-by: poma <pomidorabelisima@gmail.com>
Reviewed-by: Vladimir Davydov <vdavydov@parallels.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Cc: stable@vger.kernel.org
Signed-off-by: Christoph Hellwig <hch@lst.de>