dt-bindings: pinctrl-zynq: Replace 'io-standard' with 'power-source'

Replace custom pin configuration option 'io-standard' with generic property
'power-source' for Zynq pinctrl also add dt-binding file contains pin
configuration defines for Zynq pinctrl.

Signed-off-by: Sai Krishna Potthuri <lakshmi.sai.krishna.potthuri@xilinx.com>
Link: https://lore.kernel.org/r/1626868353-96475-3-git-send-email-lakshmi.sai.krishna.potthuri@xilinx.com


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