sh: intc - add support for SH7785

This patch converts the cpu specific interrupt setup code for sh7785
from intc2 to intc. New vectors are also added to match the information
provided by the datasheet.

No IRQ/IRL pin vectors are enabled by default. Use plat_irq_setup_pins()
to select between IRL and IRQ mode.

Signed-off-by: Magnus Damm <damm@igel.co.jp>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>