arm64: dts: allwinner: h616: Add NMI device node

Add device node for the H616 Non Maskable Interrupt (NMI) controller.
This controller is present on all H616 boards and derivatives such as
the T507 and H700. Note that on the H616 no NMI pad is exposed.

Reviewed-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Chris Morgan <macromorgan@hotmail.com>
Acked-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Link: https://lore.kernel.org/r/20240418181615.1370179-3-macroalpha82@gmail.com
Signed-off-by: Jernej Skrabec <jernej.skrabec@gmail.com>