Move misplaced comment

Signed-off-by: Hanno Becker <hanno.becker@arm.com>
diff --git a/library/ssl_tls13_keys.c b/library/ssl_tls13_keys.c
index 88b1b8a..2128f83 100644
--- a/library/ssl_tls13_keys.c
+++ b/library/ssl_tls13_keys.c
@@ -255,12 +255,14 @@
     }
     else
     {
-        /* This should never happen since this function is internal
-         * and the code sets `context_already_hashed` correctly.
-         * Let's double-check nonetheless to not run at the risk
-         * of getting a stack overflow. */
         if( clen > sizeof(hashed_context) )
+        {
+            /* This should never happen since this function is internal
+             * and the code sets `context_already_hashed` correctly.
+             * Let's double-check nonetheless to not run at the risk
+             * of getting a stack overflow. */
             return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+        }
 
         memcpy( hashed_context, ctx, clen );
     }