audio_parser: fix assertion failure in audio format mask parser

Use audio_format_mask_valid() to verify a mask.

src/audio_parser.c

@@ -192,7 +192,8 @@ audio_format_parse(struct audio_format *dest, const char *src,
 	}
 
 	audio_format_init(dest, rate, sample_format, channels);
-	assert(audio_format_valid(dest));
+	assert(mask ? audio_format_mask_valid(dest)
+	       : audio_format_valid(dest));
 
 	return true;
 }