pinctrl: renesas: r8a779g0: Add support for AVB/TSN power-sources

Add support for configuring the I/O voltage levels of the Ethernet AVB
and Ethernet TSN pins on the R-Car V4H SoC.  "PIN_VDDQ_AVB[012]" and
"PIN_VDDQ_TSN0" can be configured for 1.8V or 2.5V operation.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/c046e0be7d26302061d7aa629180a451734ddf8f.1678271030.git.geert+renesas@glider.be