Fix compilation warning on fifisdr.c

rigs/kit/fifisdr.c

@@ -653,7 +653,7 @@ static int fifisdr_set_level(RIG *rig, vfo_t vfo, setting_t level, value_t val)
         /* Transform Hamlib enum value to FiFi-SDR selector */
         fifi_agc = 0;
 
-        switch ((enum agc_level_e)val.i)
+        switch (val.i)
         {
         case RIG_AGC_OFF:       fifi_agc = 0;   break;