Add MBEDTLS_ALLOW_PRIVATE_ACCESS to tests drivers

Signed-off-by: Mateusz Starzyk <mateusz.starzyk@mobica.com>
diff --git a/tests/src/drivers/test_driver_mac.c b/tests/src/drivers/test_driver_mac.c
index 69af107..439943c 100644
--- a/tests/src/drivers/test_driver_mac.c
+++ b/tests/src/drivers/test_driver_mac.c
@@ -17,6 +17,8 @@
  *  limitations under the License.
  */
 
+#define MBEDTLS_ALLOW_PRIVATE_ACCESS
+
 #if !defined(MBEDTLS_CONFIG_FILE)
 #include "mbedtls/config.h"
 #else