[SCSI] scsi_debug: stop including drivers/scsi/scsi.h

This converts scsi_debug to include header files in include/scsi/
instead of drivers/scsi/scsi.h.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Acked-by: Douglas Gilbert <dougg@torque.net>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>