sh: Enable GENERIC_HARDIRQS_NO__DO_IRQ for all SuperH machines

After the recent changes to switch SuperH board support over to irq_chip
it is now possible to set GENERIC_HARDIRQS_NO__DO_IRQ for all SuperH
boards.

Signed-off-by: Matt Fleming <mjf@gentoo.org>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>