misc_utils/trx_burst_if: get rid of built-in timeslot filter

Since the API of 'Timeslot Filter' block was exposed, we can
get rid of built-in timeslot filter and use the proper methods.
diff --git a/python/trx/radio_if.py b/python/trx/radio_if.py
index 661025a..5791f42 100644
--- a/python/trx/radio_if.py
+++ b/python/trx/radio_if.py
@@ -98,6 +98,9 @@
 		self.gsm_clck_ctrl = grgsm.clock_offset_control(
 			shift_fc, self.samp_rate, osr = 4)
 
+		self.gsm_ts_filter = grgsm.burst_timeslot_filter(0)
+		self.gsm_ts_filter.set_policy(grgsm.FILTER_POLICY_DROP_ALL)
+
 		self.gsm_trx_burst_if = grgsm.trx_burst_if(
 			self.trx_remote_addr, str(self.trx_base_port))
 
@@ -115,6 +118,9 @@
 			(self.gsm_input, 'ctrl_in'))
 
 		self.msg_connect((self.gsm_receiver, 'C0'),
+			(self.gsm_ts_filter, 'in'))
+
+		self.msg_connect((self.gsm_ts_filter, 'out'),
 			(self.gsm_trx_burst_if, 'bursts'))
 
 	def check_available(self):