Document RZ/V2L (R9A07G054) IRQC bindings. The RZ/V2L IRQC block is
identical to one found on the RZ/G2L SoC. No driver changes are
required as generic compatible string "renesas,rzg2l-irqc" will be
used as a fallback.

While at it, update the comment "# RZ/G2L" to "# RZ/G2{L,LC}" for
"renesas,r9a07g044-irqc" compatible string as both RZ/G2L and
RZ/G2LC SoC's use the common SoC DTSI and have the same IRQC block.
Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220718193745.7472-1-prabhakar.mahadev-lad.rj@bp.renesas.com