sh: Switch HD64461 from hw_interrupt_type to irq_chip

Use struct irq_chip for the interrupt handler for the HD64461. Also
convert some in{b,w} and out{b,w} calls to the equivalent __raw_* calls.
Include <linux/io.h> and not <asm/io.h> to stop checkpatch.pl
complaining.

This change should now allow machines with HD64461 to define
GENERIC_HARDIRQS_NO__DO_IRQ.

Acked-by: Kristoffer Ericson <Kristoffer.Ericson@gmail.com>
Signed-off-by: Matt Fleming <mjf@gentoo.org>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>