ms_srs: turn tx/rx_gain into INT and make them optional

when they are greater than 0 they are written as config paramter.
if they are -1 they are disbaled and automatic gain calibration is
used.

Change-Id: I473ff3ae679784178574d2f76b612dbf77180490
diff --git a/src/osmo_gsm_tester/templates/srsue.conf.tmpl b/src/osmo_gsm_tester/templates/srsue.conf.tmpl
index a922dc8..0250f2b 100644
--- a/src/osmo_gsm_tester/templates/srsue.conf.tmpl
+++ b/src/osmo_gsm_tester/templates/srsue.conf.tmpl
@@ -39,8 +39,12 @@
 dl_earfcn = 2850
 % endif
 freq_offset = ${ue.freq_offset}
+% if int(ue.tx_gain) > 0:
 tx_gain = ${ue.tx_gain}
+% endif
+% if int(ue.rx_gain) > 0:
 rx_gain = ${ue.rx_gain}
+% endif
 
 #nof_radios = 1
 nof_antennas = ${ue.num_antennas}