src/southbridge: Use 'include <stdlib.h>' when appropriate

Also, including <types.h>, is supposed to provide stdint and stddef.

Change-Id: I7e1a3483aae0e3f0a7bc2eb2c1862ae7a325fd9c
Signed-off-by: Elyes HAOUAS <ehaouas@noos.fr>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/33683
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Martin Roth <martinroth@google.com>
diff --git a/src/southbridge/amd/cimx/sb800/smbus_spd.c b/src/southbridge/amd/cimx/sb800/smbus_spd.c
index a6881bb..a574072 100644
--- a/src/southbridge/amd/cimx/sb800/smbus_spd.c
+++ b/src/southbridge/amd/cimx/sb800/smbus_spd.c
@@ -15,7 +15,7 @@
 
 #include <device/pci_def.h>
 #include <device/device.h>
-#include <stdlib.h>
+#include <stddef.h>
 #include <OEM.h>		/* SMBUS0_BASE_ADDRESS */
 
 /* warning: Porting.h includes an open #pragma pack(1) */