libc: Fix all includes in codebase

The codebase was using non-standard headers. It is needed to replace
them by the correct ones so that we can use the new libc headers.

Change-Id: I530f71d9510cb036e69fe79823c8230afe890b9d
Acked-by: Sumit Garg <sumit.garg@linaro.org>
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>
diff --git a/plat/rockchip/rk3399/drivers/dp/cdn_dp.c b/plat/rockchip/rk3399/drivers/dp/cdn_dp.c
index f1a5e2b..2adab8f 100644
--- a/plat/rockchip/rk3399/drivers/dp/cdn_dp.c
+++ b/plat/rockchip/rk3399/drivers/dp/cdn_dp.c
@@ -4,6 +4,7 @@
  * SPDX-License-Identifier: BSD-3-Clause
  */
 
+#include <cdefs.h>
 #include <cdn_dp.h>
 #include <smccc.h>
 #include <stdlib.h>