Provide a compatible string in the config nodes that U-Boot can use to
help decide which configuration to use with SPL_LOAD_FIT_FULL=y and
FIT_BEST_MATCH=y.
Signed-off-by: Simon Glass <sjg@chromium.org> Signed-off-by: Jonas Karlman <jonas@kwiboo.se> Reviewed-by: Kever Yang <kever.yang@rock-chips.com> Reviewed-by: Quentin Schulz <quentin.schulz@cherry.de>