binman: Add support for selecting firmware to use with split-elf

In some cases it is desired for SPL to start TF-A instead of U-Boot
proper. Add support for a new property fit,firmware that picks a
valid entry and prepends the remaining valid entries to the
loadables list generated by the split-elf generator.

Signed-off-by: Jonas Karlman <jonas@kwiboo.se>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
4 files changed