refactor(mbedtls): allow platform to specify their config file

Common mbedTLS implementation include the fixed configuration
file of mbedTLS and that does not gives flexilibility to the
platform to include their own mbedTLS configuration.
Hence changes are done so that platform can include their own
mbedTLS configuration file.

Signed-off-by: Lucian Paul-Trifu <lucian.paul-trifu@arm.com>
Signed-off-by: Manish V Badarkhe <manish.badarkhe@arm.com>
Change-Id: I04546589f67299e26b0a6a6e151cdf1fdb302607
diff --git a/drivers/auth/dualroot/cot.c b/drivers/auth/dualroot/cot.c
index e1e47bc..8368503 100644
--- a/drivers/auth/dualroot/cot.c
+++ b/drivers/auth/dualroot/cot.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020, Arm Limited. All rights reserved.
+ * Copyright (c) 2020-2022, Arm Limited. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -8,7 +8,7 @@
 
 #include <platform_def.h>
 
-#include <drivers/auth/mbedtls/mbedtls_config.h>
+#include MBEDTLS_CONFIG_FILE
 #include <drivers/auth/auth_mod.h>
 #include <tools_share/dualroot_oid.h>