colibri_vf: Add separate defconfig for device tree support

Most of the drivers available for Vybrid are not yet converted
to OF model to use device tree model, only few drivers
like SPI and GPIO drivers use device trees.
Add separate defconfig for who needs to use device tree model.
Later this can be integrated to single defconfig.

Acked-by: Stefan Agner <stefan@agner.ch>
Signed-off-by: Bhuvanchandra DV <bhuvanchandra.dv@toradex.com>