ARM: 7023/1: L2x0: Add interrupts property to OF binding

Following the discussion here:
http://lists.ozlabs.org/pipermail/devicetree-discuss/2011-August/007301.html

The L2x0 L2 Cache Controllers support a combined interrupt line
which can be used for several events (e.g. read/write/parity errors on
tag/data RAM, event counter increment/overflow). Unfortunately the
OF binding added in c519ecf2 ("ARM: 7009/1: l2x0: Add OF based
initialization") does not represent the interrupt.

This patch adds an "interrupts" property to the L2x0 OF binding,
representing the combined interrupt line.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Rob Herring <rob.herring@calxeda.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Cc: Grant Likely <grant.likely@secretlab.ca>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Olof Johansson <olof@lixom.net>
Cc: Barry Song <21cnbao@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>