boot: Pass just the FDT argument to label_process_fdt()

Since this function only adjusts one element of the bootm command, pass
just that. This will make it easier to refactor things to remove the
bootm command.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Quentin Schulz <quentin.schulz@cherry.de>
1 file changed