dt-bindings: timer: renesas,tmu: Make interrupt-names required

Now all in-tree users have been updated with interrupt-names properties
according to commit 0076a37a ("dt-bindings: timer: renesas,tmu:
Document input capture interrupt"), make interrupt-names required.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/65fdd0425be0cc1bae9e6f7996aceaa5ad34e510.1716985947.git.geert+renesas@glider.be


Signed-off-by: Rob Herring (Arm) <robh@kernel.org>