pinctrl: renesas: rzg2l: Refactor OEN register PWPR handling

pinctrl: renesas: rzg2l: Refactor OEN register PWPR handling

Extract the OEN register write with PWPR protection logic into a helper
function to eliminate code duplication between rzg2l_write_oen() and
rzg2l_pinctrl_resume_noirq().

Introduce rzg2l_oen_write_with_pwpr() helper that encapsulates the
PWPR unlock, OEN register write, and PWPR lock sequence. This helper
must be called with pctrl->lock already held by the caller.

Reported-by: Pavel Machek <pavel@denx.de>
Closes: https://lore.kernel.org/cip-dev/OS9PR01MB16368C765305362F5F4132759FFC4A@OS9PR01MB16368.jpnprd01.prod.outlook.com/T/#u
Signed-off-by: John Madieu <john.madieu.xa@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://patch.msgid.link/20251106080758.36645-1-john.madieu.xa@bp.renesas.com
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>