dt-bindings: timer: Convert jcore,pit to DT schema

Convert the J-Core PIT Timer binding to DT schema format. It's a
straight-forward conversion.

Since the 'reg' entries are based on number of cores, we can't put
constraints on it.

Signed-off-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://lore.kernel.org/r/20250506022253.2587999-1-robh@kernel.org


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