This adds a bunch of unit tests for the "fdt apply" command.
They've all been run successfully in the sandbox. However, as you still
require an out-of-tree dtc with overlay support, this is disabled by
Acked-by: Simon Glass <firstname.lastname@example.org>
Acked-by: Pantelis Antoniou <email@example.com>
Signed-off-by: Maxime Ripard <firstname.lastname@example.org>