scsi-resolve-sg-buffer-const-ness-issue-fix

fix very broken build

Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Dave Gordon <david.s.gordon@intel.com>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>