sh: intc - add support for SH7710

This patch converts the cpu specific interrupt setup code
for sh7710 from ipr to intc. While at it new vectors are added
to match the information provided by the datasheet. Version two
simplifies the Kconfig part.

Vectors for IRQ4 and IRQ5 are enabled by default. Use
plat_irq_setup_pins() if pins IRQ0-3 should be used in IRQ mode.

This patch also adds sh7710 specific platform data for the rtc
driver. The base address of SCIF1 is adjusted to match the
datasheet.

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