ms_amarisoft: fix various regressions

this patch fixes some regressions in the Amarisoft UE class,
the config template, etc. that have been undetected bc we never
executed tests with it.

Change-Id: I397e675a4018acf3372a3b7e29fd864703b2b919
diff --git a/sysmocom/defaults.conf b/sysmocom/defaults.conf
index a9015f7..7704857 100644
--- a/sysmocom/defaults.conf
+++ b/sysmocom/defaults.conf
@@ -180,6 +180,7 @@
 amarisoftue:
   tx_gain: 89
   rx_gain: 60
+  rf_dev_sync: none
 
 iperf3cli:
   time: 60