ARM: 6138/1: Add support for 10 hardirq bits

This patch adds support for 10 hardirq bits to
the ARM architecture. Needed by the SH-Mobile
ARM processor sh7372 that has more than 512 IRQs.

Signed-off-by: Magnus Damm <damm@opensource.se>
Acked-by: Eric Miao <eric.y.miao@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>