fixes an issue with clock source

- command line paramter --clock-source can only be set at UE (removed this option from gNB)
 - at gNB use clock_source from RU section in config file
 - in both cases if clock_source is present in usrp_args, it will override clock_source

executables/nr-softmodem.c

@@ -106,7 +106,6 @@ int config_sync_var=-1;
 #endif
 volatile int             oai_exit = 0;
 
-static clock_source_t clock_source = internal;
 static int wait_for_sync = 0;
 
 unsigned int mmapped_dma=0;