sh: intc - add support for SH7706, SH7707, SH7708, SH7709

This patch unifies the cpu specific interrupt setup code for
sh7706, sh7707, sh7708 and sh7709 and moves the code into a new
file called setup-sh770x.c.  It makes sense to share the setup code
between these processors because most hardware blocks are identical
from a software point of view. With this patch the sh770x processors
now have a complete set of vectors that match with the information
provided by the data sheets. This is a big improvement for sh7708.

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 unifies the platform device setup code which means
that the rtc driver now has platform data for all sh770x processors.

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