coding: fix comments for detect_afs_sid_{first,update,onset}

Change-Id: I42edc3caee09c1a4bebecc41e8be46914dc7f8ef
Related: SYS#5853
diff --git a/src/coding/gsm0503_amr_dtx.c b/src/coding/gsm0503_amr_dtx.c
index 7069b96..b149330 100644
--- a/src/coding/gsm0503_amr_dtx.c
+++ b/src/coding/gsm0503_amr_dtx.c
@@ -163,19 +163,19 @@
 	return *n_errors < *n_bits_total / 8;
 }
 
-/* Detect a an FR AMR SID_FIRST frame by its identifcation marker */
+/* Detect an FR AMR SID_FIRST frame by its identifcation marker */
 static bool detect_afs_sid_first(int *n_errors, int *n_bits_total, const ubit_t * ubits)
 {
 	return detect_afs_id_marker(n_errors, n_bits_total, ubits, 32, 53, id_marker_0, 9);
 }
 
-/* Detect an FR AMR SID_FIRST frame by its identification marker */
+/* Detect an FR AMR SID_UPDATE frame by its identification marker */
 static bool detect_afs_sid_update(int *n_errors, int *n_bits_total, const ubit_t * ubits)
 {
 	return detect_afs_id_marker(n_errors, n_bits_total, ubits, 36, 53, id_marker_0, 9);
 }
 
-/* Detect an FR AMR SID_FIRST frame by its repeating coded inband data */
+/* Detect an FR AMR ONSET frame by its repeating coded inband data */
 static bool detect_afs_onset(int *n_errors, int *n_bits_total, const ubit_t * ubits)
 {
 	bool rc;