dyn TS: split dyn_pdch_init() for new dyn type and rename

Init both TCH/F_PDCH and TCH/F_TCH/H_PDCH via dyn_ts_init(), which
refactors dyn_pdch_init().

Make dyn_ts_switchover_start from abis_rsl.c public in abis_rsl.h, so we can
start the initial switchover to PDCH from dyn_ts_init(); in abis_rsl.h include
gsm_utils.h for enum gsm_phys_chan_config.

Change-Id: I5c0b257ba8ff0e9c9a2268681a84b0681a778368
diff --git a/openbsc/src/libbsc/abis_rsl.c b/openbsc/src/libbsc/abis_rsl.c
index 8af3b9b..b84a0b5 100644
--- a/openbsc/src/libbsc/abis_rsl.c
+++ b/openbsc/src/libbsc/abis_rsl.c
@@ -55,8 +55,6 @@
 
 static int rsl_send_imm_assignment(struct gsm_lchan *lchan);
 static void error_timeout_cb(void *data);
-static int dyn_ts_switchover_start(struct gsm_lchan *lchan,
-				   enum gsm_phys_chan_config to_pchan);
 static int dyn_ts_switchover_continue(struct gsm_lchan *lchan);
 static int dyn_ts_switchover_failed(struct gsm_lchan *lchan, int rc);
 static void dyn_ts_switchover_complete(struct gsm_lchan *lchan);
@@ -2321,8 +2319,8 @@
 	return rc;
 }
 
-static int dyn_ts_switchover_start(struct gsm_lchan *lchan,
-				   enum gsm_phys_chan_config to_pchan)
+int dyn_ts_switchover_start(struct gsm_lchan *lchan,
+			    enum gsm_phys_chan_config to_pchan)
 {
 	int ss;
 	struct gsm_bts_trx_ts *ts = lchan->ts;