arm64: dts: renesas: v2mevk2: Add PWC support

The RZ/V2M EVK uses the PWC IP to control external power supplies
and the I/O voltage for the uSD card.

This patch enables the PWC node, and it also enables the poweroff
features since PWC is actually used to control the board power
rails.

Signed-off-by: Fabrizio Castro <fabrizio.castro.jz@renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20230118144747.24968-3-fabrizio.castro.jz@renesas.com


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