sh: dma-sh updates for multi IRQ and new SH-4A CPUs.

This adds DMA support for newer SH-4A CPUs, particularly SH7763/64/80/85.

This also enables multi IRQ support for platforms that have multiple
vectors bound to the same IRQ source.

Signed-off-by: Nobuhiro Iwamatsu <iwamatsu.nobuhiro@renesas.com>
Signed-off-by: Yoshihiro Shimoda <shimoda.yoshihiro@renesas.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>