dt-bindings: mfd: ti,j721e-system-controller: Add compatible string for AM654

Add the child nodes that can be found under this node. Then as done
for other similar devices (J7200 and J721s2) add support for the AM654
system controller to this binding.

Signed-off-by: Andrew Davis <afd@ti.com>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://lore.kernel.org/r/20250421214620.3770172-2-afd@ti.com


Signed-off-by: Nishanth Menon <nm@ti.com>