arm: dts: spear600: Fix clcd interrupt

Interrupt 12 of the Interrupt controller belongs to the SMI controller,
the right one for the display controller is the interrupt 13.

Fixes: 8113ba91 ("ARM: SPEAr: DT: Update device nodes")
Signed-off-by: Kory Maincent <kory.maincent@bootlin.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>