superio: Use 'include <stdlib.h>' when appropriate

Change-Id: I55e7b680e128f29a9fd549edfb676e6571330677
Signed-off-by: Elyes HAOUAS <ehaouas@noos.fr>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/32830
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Felix Held <felix-coreboot@felixheld.de>
diff --git a/src/superio/smsc/lpc47m15x/superio.c b/src/superio/smsc/lpc47m15x/superio.c
index 7b7623f..40eb7d2 100644
--- a/src/superio/smsc/lpc47m15x/superio.c
+++ b/src/superio/smsc/lpc47m15x/superio.c
@@ -19,7 +19,7 @@
 #include <device/pnp.h>
 #include <superio/conf_mode.h>
 #include <pc80/keyboard.h>
-#include <stdlib.h>
+
 #include "lpc47m15x.h"
 
 /* Forward declarations */