dt-bindings: timer: brcm,kona-timer: convert to YAML

Convert Broadcom Kona family timer bindings to DT schema.

Changes during conversion:
  - drop deprecated compatible (it's been deprecated for ~10 years)

Signed-off-by: Stanislav Jakubek <stano.jakubek@gmail.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20230618144635.GA22166@standask-GA-A55M-S2HP