trx/radio_if.py: drop useless import of osmosdr

Change-Id: Iacd5ca118957e3ecf05df81f511b17bb9a8982b5
diff --git a/python/trx/radio_if.py b/python/trx/radio_if.py
index 119b237..2648cc9 100644
--- a/python/trx/radio_if.py
+++ b/python/trx/radio_if.py
@@ -26,7 +26,6 @@
 import pmt
 import time
 import grgsm
-import osmosdr
 
 from math import pi