ARM: dts: r8a7740: use GIC_* defines

Use GIC_* defines for GIC interrupt cells in r8a7740 device tree.
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Acked-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>