dt-bindings: serial: renesas,scif: Make 'interrupt-names' property as required

As all the SoCs having multiple interrupts have 'interrupt-names' property
in their respective DTSIs, make 'interrupt-names' property as required
so that we can validate them using dtbs_check.

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20240604170513.522631-4-prabhakar.mahadev-lad.rj@bp.renesas.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>