layout.c: Use the libflashrom function for included arguments

Use the libflashrom function to determine whether included regions are
present in the layout file.

Change-Id: I5e9375baad763612e179262973413a7161acba8b
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/c/flashrom/+/31244
Tested-by: Nico Huber <nico.h@gmx.de>
Reviewed-by: Nico Huber <nico.h@gmx.de>
1 file changed