ARM: mach-shmobile: Break out INTC IRQ code

Add INTC_IRQ_PINS_16() and INTC_IRQ_PINS_32() to mach/intc.h.
These macros define 16 or 32 external IRQ pins on a certain
memory base address. Can be used with INTCA or INTCS.

Signed-off-by: Magnus Damm <damm@opensource.se>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>