irqchip/renesas-rzg2l: Rename rzg2l_tint_eoi()

Rename rzg2l_tint_eoi()->rzg2l_clear_tint_int() and simplify the code by
removing redundant priv and hw_irq local variables.

Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>