Add "interrupt-names" properties to SCIF nodes for clarity.

This allows us to update the DT bindings to mark the "interrupt-names"
property required for all SoCs which have multiple interrupts, and to
validate the DTBs using dtbs_check.
Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20240318174345.46824-1-prabhakar.mahadev-lad.rj@bp.renesas.comSigned-off-by: Geert Uytterhoeven <geert+renesas@glider.be>