amarisoft_sib23.asn.tmpl: set p-b value in SIB23 depending on TM

this fixes a wrong p-b value used for TM2 and above

Change-Id: I89c557c456f3330f491cc66bc4931a0234bf6e02
diff --git a/src/osmo_gsm_tester/templates/amarisoft_sib23.asn.tmpl b/src/osmo_gsm_tester/templates/amarisoft_sib23.asn.tmpl
index c08b645..f26cebd 100644
--- a/src/osmo_gsm_tester/templates/amarisoft_sib23.asn.tmpl
+++ b/src/osmo_gsm_tester/templates/amarisoft_sib23.asn.tmpl
@@ -37,7 +37,11 @@
             },
             pdsch-ConfigCommon {
               referenceSignalPower -5,
+              % if int(enb.get('transmission_mode')) == 1:
+              p-b 0
+              % else:
               p-b 1
+              % endif
             },
             pusch-ConfigCommon {
               pusch-ConfigBasic {