arm64: dts: renesas: r8a77970: Add secondary CA53 CPU core

Add a device node for the second Cortex-A53 CPU core on the Renesas
R-Car V3M (r8a77970) SoC, and adjust the interrupt delivery masks for
ARM Generic Interrupt Controller and Architectured Timer.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>