pinctrl: imx: Disallow driver unbind

Performing the 'unbind' operation on pinctrl drivers is
not a sensible usecase, so pass the suppress_bind_attrs
atribute to prevent it.

Signed-off-by: Fabio Estevam <festevam@gmail.com>
Link: https://lore.kernel.org/r/20210328183034.555702-2-festevam@gmail.com


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