Add reverse_endian field to struct audio_format and handle conversion

src/filter/convert_filter_plugin.c

@@ -149,6 +149,7 @@ convert_filter_set(struct filter *_filter,
 	assert(audio_format_valid(&filter->out_audio_format));
 	assert(out_audio_format != NULL);
 	assert(audio_format_valid(out_audio_format));
+	assert(filter->in_audio_format.reverse_endian == 0);
 
 	filter->out_audio_format = *out_audio_format;
 }