sh: landisk mv_nr_irqs definition.

Fix up the landisk build. When NR_IRQS was removed, landisk got missed
in the updates. Update the machvec for the landisk IRQs to get it
working again.

Signed-off-by: kogiidena <kogiidena@eggplant.ddo.jp>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>