pcu: Enable 'egprs only' vty option if egprs requested

Change-Id: Idd0b5bf8769d693480268c0a0b89dbfd63779e48
diff --git a/src/osmo_gsm_tester/pcu_sysmo.py b/src/osmo_gsm_tester/pcu_sysmo.py
index 3f6149d..8998622 100644
--- a/src/osmo_gsm_tester/pcu_sysmo.py
+++ b/src/osmo_gsm_tester/pcu_sysmo.py
@@ -111,7 +111,8 @@
         config.overlay(values, {
                         'osmo_pcu_sysmo': {
                             'bts_addr': self.sysmobts.remote_addr(),
-                            'pcu_socket_path': self.sysmobts.pcu_socket_path()
+                            'pcu_socket_path': self.sysmobts.pcu_socket_path(),
+                            'egprs_enabled': self.egprs_enabled(),
                         }
         })
         config.overlay(values, { 'osmo_pcu_sysmo': self.conf })