layout: Tidy up the include-args API

Move all forward declarations into `layout.h`, use consistent naming.

Change-Id: I0e87c9d91b9bc4d78f9cee98caff6985803f7be7
Signed-off-by: Nico Huber <nico.h@gmx.de>
Original-Reviewed-on: https://review.coreboot.org/c/flashrom/+/54287
Original-Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Original-Reviewed-by: Anastasia Klimchuk <aklm@chromium.org>
Original-Reviewed-by: Edward O'Callaghan <quasisec@chromium.org>
Reviewed-on: https://review.coreboot.org/c/flashrom-stable/+/72223
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/layout.c b/layout.c
index 79965b3..804e4fe 100644
--- a/layout.c
+++ b/layout.c
@@ -186,7 +186,7 @@
 	return 0;
 }
 
-void layout_cleanup(struct layout_include_args **args)
+void cleanup_include_args(struct layout_include_args **args)
 {
 	struct layout_include_args *tmp;