pinctrl: renesas: rzg2l: Unify OEN handling across RZ/{G2L,V2H,V2N}

Unify the OEN handling on RZ/V2H(P) and RZ/V2N SoCs by reusing the existing
rzg2l_read_oen and rzg2l_write_oen functions from RZ/G2L. Add a
pin_to_oen_bit callback in rzg2l_pinctrl_data to look up per-pin OEN bit
positions, and introduce an oen_pwpr_lock flag in the hwcfg to manage PWPR
locking on SoCs that require it (RZ/V2H(P) family). Remove the hardcoded
PFC_OEN define and obsolete per-SoC OEN helpers.

Also drop redundant checks for the OEN offset in the suspend/resume paths,
as all supported SoCs now provide a valid offset through the `regs.oen`
field.

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/20250806195555.1372317-6-prabhakar.mahadev-lad.rj@bp.renesas.com


Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>