audiounit_ios: remove dead code

At line 580 above we return an error if the format is S/PDIF.

modules/audio_output/audiounit_ios.m

@@ -623,13 +623,6 @@ Start(audio_output_t *p_aout, audio_sample_format_t *restrict fmt)
     if (ret != VLC_SUCCESS)
         goto error;
 
-    if (AOUT_FMT_SPDIF(fmt))
-    {
-        if (p_sys->au_dev != AU_DEV_ENCODED
-         || (port_type != PORT_TYPE_USB && port_type != PORT_TYPE_HDMI))
-            goto error;
-    }
-
     p_aout->current_sink_info.headphones = port_type == PORT_TYPE_HEADPHONES;
 
     p_sys->au_unit = au_NewOutputInstance(p_aout, kAudioUnitSubType_RemoteIO);