dt-bindings: interrupt-controller: renesas,rzg2l-irqc: Document RZ/G2UL SoC

Document RZ/G2UL (R9A07G043U) IRQC bindings. The IRQC block on RZ/G2UL SoC
is almost identical to one found on the RZ/G2L SoC the only difference
being it can support BUS_ERR_INT for which it has additional registers.
Hence new generic compatible string "renesas,r9a07g043u-irqc" is added
for RZ/G2UL SoC.

Now that we have additional interrupt for RZ/G2UL and RZ/Five SoC
interrupt-names property is added so that we can parse them based on
names.

While at it updated the example node to four spaces and added
interrupt-names property.
Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20231006121058.13890-1-prabhakar.mahadev-lad.rj@bp.renesas.com