osmo-trx: Fix random filler command line option.

Filler types was of "bool" type, which prevented it from taking values greter
than 1. And RAND filler type has integer value of 2, which was casted to 1 on
assigning, which led to a normal filler table being used instead of the RAND
one.
diff --git a/Transceiver52M/Transceiver.h b/Transceiver52M/Transceiver.h
index 8bcd8e5..4f6aa69 100644
--- a/Transceiver52M/Transceiver.h
+++ b/Transceiver52M/Transceiver.h
@@ -149,7 +149,7 @@
     IDLE	       ///< timeslot is an idle (or dummy) burst
   } CorrType;
 
-  enum {
+  enum FillerType {
     FILLER_DUMMY,
     FILLER_ZERO,
     FILLER_RAND,