Add a driver for the Renesas RZ/G2L Interrupt Controller.

This supports external pins being used as interrupts. It supports
one line for NMI, 8 external pins and 32 GPIO pins (out of 123)
to be used as IRQ lines.
Signed-off-by: NLad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Signed-off-by: NMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220707182314.66610-4-prabhakar.mahadev-lad.rj@bp.renesas.com