ARM: imx_*_defconfig: Fix i.MX pinctrl enablement

When the i.MX pinctrl drivers were made user controllable by 17d210018914
("ARM: imx: Allow user to disable pinctrl") the select of pinctrl by the
arch code was removed. This change means that for the i.MX specific
defconfigs nothing enables the base PINCTRL Kconfig and things that depend
on it (eg, audio on the i.MX6 UDOO boards) stop working. Explicitly enable
PINCTRL in these configs to restore functionality with them.

Fixes: 17d210018914 ("ARM: imx: Allow user to disable pinctrl")
Signed-off-by: Mark Brown <broonie@kernel.org>