l1sap: Add RSSI, BER and quarter-bit accurate timing to PH-RACH.ind

Let's extend PH-RACH.ind with some useful data across the L1SAP
boundary.

Change-Id: I9439810c3a3ad89ea0302753617b850749af887c
Related: OS#3003
diff --git a/include/osmocom/gsm/l1sap.h b/include/osmocom/gsm/l1sap.h
index 1bc1818..18ad7d2 100644
--- a/include/osmocom/gsm/l1sap.h
+++ b/include/osmocom/gsm/l1sap.h
@@ -64,6 +64,10 @@
 	uint32_t fn;		/*!< GSM Frame Number at time of RA */
 	uint8_t is_11bit;	/*!< no.of bits in RACH*/
 	enum ph_burst_type burst_type; /*!< type of burst*/
+	/* elements added on 2018-02-26 */
+	int8_t rssi;		/*!< RSSI of RACH indication */
+	uint16_t ber10k;	/*!< BER in units of 0.01% */
+	int16_t acc_delay_256bits;/* !< Burst TA Offset in 1/256th bits */
 };
 
 /*! for PH-[UNIT]DATA.{req,ind} | PH-RTS.ind */