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/ssl_tls13_generic.c b/library/ssl_tls13_generic.c
index 756d529..e88c00a 100644
--- a/library/ssl_tls13_generic.c
+++ b/library/ssl_tls13_generic.c
@@ -13,7 +13,7 @@
 
 #include "mbedtls/error.h"
 #include "debug_internal.h"
-#include "mbedtls/private/oid.h"
+#include "mbedtls/oid.h"
 #include "mbedtls/platform.h"
 #include "mbedtls/constant_time.h"
 #include "psa/crypto.h"