ARM: mvebu: use GIC_{SPI,PPI} in Armada 375/38x DTs

Instead of hardcoding 0 and 1 to indicate SPI and PPI GIC interrupts,
use the definitions of <dt-bindings/interrupt-controller/arm-gic.h> to
clarify the Device Tree code.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Acked-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>