x264enc: simplify template caps

No need to make an array for one single element.

ext/x264/gstx264enc.c

@@ -411,7 +411,7 @@ static GstStaticPadTemplate src_factory = GST_STATIC_PAD_TEMPLATE ("src",
         "framerate = (fraction) [0/1, MAX], "
         "width = (int) [ 1, MAX ], " "height = (int) [ 1, MAX ], "
         "stream-format = (string) { avc, byte-stream }, "
-        "alignment = (string) { au }, "
+        "alignment = (string) au, "
         "profile = (string) { high-10, high, main, baseline, "
         "constrained-baseline, high-10-intra }")
     );