sh: intc - add support for SH7750 and its variants

This patch converts the cpu specific 7750 setup code to use the
new intc controller. Many new vectors are added and multiple
processor variants including 7091, 7750, 7750s, 7750r, 7751 and
7751r should all have the correct vectors hooked up.

IRLM interrupts can be enabled using ipr_irq_enable_irlm() which
now is marked as __init.

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