dt-bindings: pinctrl: imx7d: Fix PAD_CTL_DSE_X*

In the iMX7d datasheet, the PAD_CTL_DSE_X* values are different from
the documentation.

Changes since v2:
* Changed patch title to 'dt-bindings: pinctrl: imx7d:'

Signed-off-by: Christina Quast <cquast@hanoverdisplays.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Acked-by: Dong Aisheng <aisheng.dong@nxp.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>