scsi: Remove Makefile entry for oktagon files

Remove line using non-existent files which were removed in
commit 642978be

 ("[SCSI] remove m68k NCR53C9x based drivers")

[mkp: tweaked patch description]

Signed-off-by: Corentin Labbe <clabbe@baylibre.com>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>