dt-bindings: mmc: fsl-imx-esdhc: add pinctrl bindings

Add pinctrl bindings for fsl-imx-esdhc yaml

Signed-off-by: Peng Fan <peng.fan@nxp.com>
Link: https://lore.kernel.org/r/1614222604-27066-2-git-send-email-peng.fan@oss.nxp.com


Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>