audioencoders: use template subset check for accept-caps

It is faster than doing a query that propagates downstream and
should be enough

Elements: faac, gsmenc, opusenc, sbcenc, voamrwbenc, adpcmenc, sirenenc
diff --git a/ext/voamrwbenc/gstvoamrwbenc.c b/ext/voamrwbenc/gstvoamrwbenc.c
index 305f845..ae09f06 100644
--- a/ext/voamrwbenc/gstvoamrwbenc.c
+++ b/ext/voamrwbenc/gstvoamrwbenc.c
@@ -190,6 +190,8 @@
 static void
 gst_voamrwbenc_init (GstVoAmrWbEnc * amrwbenc)
 {
+  GST_PAD_SET_ACCEPT_TEMPLATE (GST_AUDIO_ENCODER_SINK_PAD (amrwbenc));
+
   /* init rest */
   amrwbenc->handle = NULL;
   amrwbenc->channels = 0;