arm64: dts: renesas: white-hawk-cpu: Add missing bootargs

This patch adds missing bootargs for R-Car V4H White Hawk board.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Link: https://lore.kernel.org/r/87k06858oe.wl-kuninori.morimoto.gx@renesas.com


Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>