apalis-tk1: enable user debug by default

Let the kernel print some debug messages when a user program
crashes due to an exception.

Signed-off-by: Stefan Agner <stefan.agner@toradex.com>
Signed-off-by: Igor Opaniuk <igor.opaniuk@toradex.com>
Reviewed-by: Oleksandr Suvorov <oleksandr.suvorov@toradex.com>
Signed-off-by: Tom Warren <twarren@nvidia.com>