pinctrl: eswin: Add EIC7700 pinctrl driver

Add support for the pin controller in ESWIN's EIC7700 SoC,
which supports pin multiplexing, pin configuration,
and rgmii voltage control.

Co-developed-by: Samuel Holland <samuel.holland@sifive.com>
Signed-off-by: Samuel Holland <samuel.holland@sifive.com>
Signed-off-by: Yulin Lu <luyulin@eswincomputing.com>
Link: https://lore.kernel.org/20250612105159.1241-1-luyulin@eswincomputing.com


Signed-off-by: Linus Walleij <linus.walleij@linaro.org>