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_msg.c b/library/ssl_msg.c
index fd7e16c..731cbc8 100644
--- a/library/ssl_msg.c
+++ b/library/ssl_msg.c
@@ -30,7 +30,7 @@
 #include "psa/crypto.h"
 
 #if defined(MBEDTLS_X509_CRT_PARSE_C)
-#include "mbedtls/private/oid.h"
+#include "mbedtls/oid.h"
 #endif
 
 /* Define a local translating function to save code size by not using too many