The RZ/G3S SoC supports configurable supply voltages for several of its
I/O interfaces. All of these interfaces support both 1.8V and 3.3V
supplies, but only the Ethernet and XSPI interfaces support a 2.5V
supply.

Voltage selection for the XSPI interface is not yet supported, so this
leaves only the Ethernet interfaces currently supporting selection of a
2.5V supply. So we need to return an error if there is an attempt to
select a 2.5V supply for any non-Ethernet interface.

Fixes: 51996952 ("pinctrl: renesas: rzg2l: Add support to select power source for Ethernet pins")
Signed-off-by: Paul Barker <paul.barker.ct@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20240417114132.6605-1-paul.barker.ct@bp.renesas.comSigned-off-by: Geert Uytterhoeven <geert+renesas@glider.be>