Remove questionable use of macro.

MBEDTLS_X509_SAFE_SNPRINTF was used after mbedtls_oid_get_numeric_string
so instead we have expanded the macro and kept the relevant code.

Signed-off-by: Agathiyan Bragadeesh <agathiyan.bragadeesh2@arm.com>
diff --git a/library/x509.c b/library/x509.c
index 18e6a18..446bf24 100644
--- a/library/x509.c
+++ b/library/x509.c
@@ -861,7 +861,8 @@
             ret = mbedtls_snprintf(p, n, "%s=", short_name);
         } else {
             if ((ret = mbedtls_oid_get_numeric_string(p, n, &name->oid)) > 0) {
-                MBEDTLS_X509_SAFE_SNPRINTF;
+                n -= ret;
+                p += ret;
                 ret = mbedtls_snprintf(p, n, "=");
                 print_hexstring = 1;
             } else {