arm64: dts: renesas: r9a09g057h44-rzv2h-evk: Add NMI pushbutton support

arm64: dts: renesas: r9a09g057h44-rzv2h-evk: Add NMI pushbutton support

RZ/V2H EVK has a user pushbutton connected to the SoC NMI pin, which
can be used to wake up the system from suspend to idle. Add a DT node
in the device tree to instantiate the gpio-keys driver for this button.

Signed-off-by: Ovidiu Panait <ovidiu.panait.rb@renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://patch.msgid.link/20251027140651.18367-1-ovidiu.panait.rb@renesas.com
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>