Using uboot version 2017.11 creates an sd card image which fails to
boot with the following error:
Missing DTB
### ERROR ### Please RESET the board ###
Updating tinkerboard default configuration to use latest uboot release
2018.07 creates a sd card image which boot fine.
Signed-off-by: Yannis Damigos <ydamigos@iccs.gr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>