dt-bindings: pinctrl: imx8m: Integrate duplicated i.MX 8M schemas

The i.MX8MM/N/P/Q IOMUXC schemas are basically the same, it does not to
have four schemas for almost the same binding.

Signed-off-by: Peng Fan <peng.fan@nxp.com>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20230104021430.3503497-1-peng.fan@oss.nxp.com


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