rsl: use 3GPP assigned payload type constants from libosmo-netif

The payload constants for AMR, EFR, GSM-FR, and GSM-HR are already
defined in libosmo-netif, there is no need to re-define them locally.

- include rtp.h from libosmo-netif in abis_rsl.c
- remove duplicate payload type constants

Change-Id: Ib6a866b29d863d6875c67748dbe6b6468941ab29
Related: OS#2728

src/osmo-bsc/abis_rsl.c

@@ -46,15 +46,11 @@
 #include <osmocom/bsc/pcu_if.h>
 #include <osmocom/bsc/bsc_api.h>
 #include <osmocom/bsc/bsc_subscr_conn_fsm.h>
+#include <osmocom/netif/rtp.h>
 
 #define RSL_ALLOC_SIZE		1024
 #define RSL_ALLOC_HEADROOM	128
 
-#define RTP_PT_GSM_FULL 3
-#define RTP_PT_GSM_HALF 96
-#define RTP_PT_GSM_EFR 97
-#define RTP_PT_AMR 98
-
 enum sacch_deact {
 	SACCH_NONE,
 	SACCH_DEACTIVATE,