layout: Add missing stdbool.h include

Change-Id: I9a413d491038b29c832011a738f3b49e029dcf6f
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/c/31013
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
diff --git a/layout.h b/layout.h
index eb54a4f..770224b 100644
--- a/layout.h
+++ b/layout.h
@@ -23,6 +23,7 @@
 
 #include <stddef.h>
 #include <stdint.h>
+#include <stdbool.h>
 
 /* Types and macros regarding the maximum flash space size supported by generic code. */
 typedef uint32_t chipoff_t; /* Able to store any addressable offset within a supported flash memory. */