irqchip/renesas-rzg2l: Use devm_reset_control_get_exclusive_deasserted()

Use devm_reset_control_get_exclusive_deasserted() to simplify
rzg2l_irqc_common_init().

Signed-off-by: Fabrizio Castro <fabrizio.castro.jz@renesas.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Link: https://lore.kernel.org/all/20250212182034.366167-3-fabrizio.castro.jz@renesas.com