Unfortunately, we had two files named oid.h - one in the main repo, and one in the tf-psa-crypto repo, and these files included the mbedtls one, so I restored the header include

Signed-off-by: Anton Matkin <anton.matkin@arm.com>
diff --git a/library/x509_oid.c b/library/x509_oid.c
index 8963529..cc0063b 100644
--- a/library/x509_oid.c
+++ b/library/x509_oid.c
@@ -14,7 +14,7 @@
  * disabled. */
 #if defined(MBEDTLS_X509_USE_C) || defined(MBEDTLS_X509_CREATE_C)
 
-#include "mbedtls/private/oid.h"
+#include "mbedtls/oid.h"
 #include "x509_oid.h"
 
 #include <stdio.h>