initialize RF UHD handler in init

lib/src/phy/rf/rf_uhd_imp.c

@@ -334,6 +334,7 @@ int rf_uhd_open_multi(char *args, void **h, uint32_t nof_channels)
       perror("malloc");
       return -1; 
     }
+    bzero(handler, sizeof(rf_uhd_handler_t));
     *h = handler; 
 
     /* Set priority to UHD threads */