irqchip/renesas-rzv2h: Add field_width to struct rzv2h_hw_info

irqchip/renesas-rzv2h: Add field_width to struct rzv2h_hw_info

On RZ/G3E the field width for TSSR register for a TINT is 16 compared to 8
on the RZ/V2H.

Add field_width to struct rzv2h_hw_info and replace the macros ICU_TSSR_K
and ICU_TSSR_TSSEL_N by a runtime evaluation:

    (32 / field_width) provides the number of tints in the TSSR register.

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>
Link: https://lore.kernel.org/all/20250224131253.134199-10-biju.das.jz@bp.renesas.com