pinctrl: nxp: DM_FLAG_PRE_RELOC by default

For NXP SoCs we have to set pinmux configuration ASAP (ideally
before relocation) to get serial console working. Without this we miss
almost the half of output (U-boot version, CPU defails, Reset cause,
DRAM details etc.).

To achieve this we need to force appropriate pinctrl drivers to get
probed before relocation.

Fixes: cd69e8ef ("colibri-imx6ull: migrate pinctrl and regulators to dtb/dm")
Signed-off-by: Igor Opaniuk <igor.opaniuk@toradex.com>
Reviewed-by: Fabio Estevam <festevam@gmail.com>
Reviewed-by: Lukasz Majewski <lukma@denx.de>
Reviewed-by: Oleksandr Suvorov <oleksandr.suvorov@toradex.com>