[SCSI] make struct scsi_{host,target}_type static

Make the needlessly global struct scsi_{host,target}_type static.

Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>