support/testing: fix TestATFAllwinner test

Fix U-Boot config snippet in TestATFAllwinner. Bump U-Boot
version to fix DTC build on hosts with gcc 10 and add
pylibfdt dependency.

Signed-off-by: Sergey Matyukevich <geomatsi@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
1 file changed