src: Use '#include <timestamp.h>' when needed

Change-Id: Ic0483982e8115ae99367d08d8ed77b8a316f5405
Signed-off-by: Elyes HAOUAS <ehaouas@noos.fr>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/34231
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>
diff --git a/src/lib/bootblock.c b/src/lib/bootblock.c
index c28a67a..3925e90a 100644
--- a/src/lib/bootblock.c
+++ b/src/lib/bootblock.c
@@ -21,6 +21,7 @@
 #include <pc80/mc146818rtc.h>
 #include <program_loading.h>
 #include <symbols.h>
+#include <timestamp.h>
 
 DECLARE_OPTIONAL_REGION(timestamp);