Add Marker to ph_tch_param

Extend struct ph_tch_param with Marker bit from RTP header to indicate
speech onset in case of DTX.

Change-Id: Ic664902630b9d335ff9abc7a9ca7249eaf80e05f
Related: OS#1750
diff --git a/include/osmocom/gsm/l1sap.h b/include/osmocom/gsm/l1sap.h
index f0e9f6c..e199efe 100644
--- a/include/osmocom/gsm/l1sap.h
+++ b/include/osmocom/gsm/l1sap.h
@@ -81,6 +81,7 @@
 	uint8_t chan_nr;	/*!< \brief Channel Number (Like RSL) */
 	uint32_t fn;		/*!< \brief GSM Frame Number */
 	int8_t rssi;		/*!< \brief RSSI of received indication */
+	uint8_t marker;		/*!< \brief RTP Marker bit (speech onset indicator) */
 };
 
 /*! \brief for PH-CONN.ind */