mach-snapdragon: generate fdtfile automatically

With just a few basic rules, we can generate the $fdtfile environment
variable to match the format used in Linux. This uses the root
compatible property inside u-boot, with specific handling for the
Dragonboard845c which is a special case, and for the qrb robotics
boards.

This is known to work on supported platforms, and lets us avoid having a
big lookup table.

Signed-off-by: Caleb Connolly <caleb.connolly@linaro.org>
1 file changed