imx8mq_evk_defconfig: Enable pinctrl driver

imx8mq_evk_defconfig: Enable pinctrl driver

The Ethernet controller is not able to initialise correctly without the
pinctrl driver.

This config setting was enabled in the initial version of this file,
but was removed by a savedefconfig resync because the parameter did not
actually exist at that point.

Fixes: 1bac199e8c87 ("configs: Resync with savedefconfig")
Signed-off-by: Chris Spencer <christopher.spencer@sea.co.uk>
Reviewed-by: Fabio Estevam <festevam@gmail.com>