vendorcode/cavium/bdk/libbdk-hal/device: Add missing <stdlib.h>

Change-Id: I64876a2b6cffdabf3e365fc07017adb14f086ecc
Signed-off-by: Elyes HAOUAS <ehaouas@noos.fr>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/37380
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/vendorcode/cavium/bdk/libbdk-hal/device/bdk-device.c

@@ -37,6 +37,7 @@
 * ARISING OUT OF USE OR PERFORMANCE OF THE SOFTWARE LIES WITH YOU.
 ***********************license end**************************************/
 #include <bdk.h>
+#include <stdlib.h>
 #include <string.h>
 #include "libbdk-arch/bdk-csrs-ap.h"
 #include "libbdk-arch/bdk-csrs-pccpf.h"