src/superio/smsc: Remove unused <stdlib.h>

Found using:
diff <(git grep -l '#include <stdlib.h>' -- src/) <(git grep -l 'memalign(\|malloc(\|calloc(\|free(' -- src/)
Change-Id: Icb747bcb702a81750a927272432666ffe603ca55
Signed-off-by: Elyes HAOUAS <ehaouas@noos.fr>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/60616
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Felix Held <felix-coreboot@felixheld.de>

src/superio/smsc/sch5545/superio.c

@@ -6,7 +6,6 @@
 #include <superio/conf_mode.h>
 #include <console/console.h>
 #include <pc80/keyboard.h>
-#include <stdlib.h>
 
 #include "sch5545.h"