pinctrl: renesas: rzg2l: Add output enable support

pinctrl: renesas: rzg2l: Add output enable support

Some of the Ethernet pins on RZ/G3S (but also valid for RZ/G2L) need to
have the direction of the IO buffer set as output for Ethernet to work
properly.  On RZ/G3S, these pins are P1_0/P7_0, P1_1/P7_1, and can have
the following Ethernet functions: TXC/TX_CLK or TX_CTL/TX_EN.

As the pins supporting output enable are SoC specific, and there is a
limited number of these pins (TXC/TX_CLK and/or TX_CTL/TX_EN), specify
output enable capable port limits in the platform-based configuration
data structure, to ensure proper validation.

The OEN support has been intantiated for RZ/G3S at the moment.

Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20231207070700.4156557-7-claudiu.beznea.uj@bp.renesas.com
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>