console/die.c: Add <stdarg.h>

Signed-off-by: Elyes Haouas <ehaouas@noos.fr>
Change-Id: I2ee8ef017d8a3409cbf47f1ed252a512dead224e
Reviewed-on: https://review.coreboot.org/c/coreboot/+/68036
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Martin L Roth <gaumless@gmail.com>

src/console/die.c

@@ -2,6 +2,7 @@
 
 #include <console/console.h>
 #include <halt.h>
+#include <stdarg.h>
 
 /*
  * The method should be overwritten in mainboard directory to signal that a