[SCSI] sun3: Remove commented out merge_contiguous_buffers

This fixes:

drivers/scsi/sun3_NCR5380.c:475: warning: ‘merge_contiguous_buffers’ defined but not used

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Sam Creasey <sammy@sammy.net>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>