pinctrl: pinctrl-zynq: Add support for 'power-source' parameter

Add support for generic pin parameter 'power-source'.
To maintain the backward compatibility, 'io-standard' parameter is still
supported in the driver.

Signed-off-by: Sai Krishna Potthuri <lakshmi.sai.krishna.potthuri@xilinx.com>
Link: https://lore.kernel.org/r/1626868353-96475-4-git-send-email-lakshmi.sai.krishna.potthuri@xilinx.com


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