dt-bindings: timer: Convert socionext,milbeaut-timer to DT schema

Convert the Socionext Milbeaut Timer binding to DT schema format.
It's a straight-forward conversion.

Signed-off-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://lore.kernel.org/r/20250506022322.2589193-1-robh@kernel.org


Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>