ms: Fix and use ms msisdn() getter

The getter method was named the same as the itnernal field, and hence
when used it would fail since the intenral field would be sleect and
fail to be called.

Change-Id: I2f631eb6256eb0e065f41d5b7531395c4a054cd8
diff --git a/src/osmo_gsm_tester/obj/ms_ofono.py b/src/osmo_gsm_tester/obj/ms_ofono.py
index b604325..0c67e0a 100644
--- a/src/osmo_gsm_tester/obj/ms_ofono.py
+++ b/src/osmo_gsm_tester/obj/ms_ofono.py
@@ -706,12 +706,12 @@
 
     def sms_send(self, to_msisdn_or_modem, *tokens):
         if isinstance(to_msisdn_or_modem, Modem):
-            to_msisdn = to_msisdn_or_modem.msisdn
+            to_msisdn = to_msisdn_or_modem.msisdn()
             tokens = list(tokens)
             tokens.append('to ' + to_msisdn_or_modem.name())
         else:
             to_msisdn = str(to_msisdn_or_modem)
-        msg = sms.Sms(self.msisdn, to_msisdn, 'from ' + self.name(), *tokens)
+        msg = sms.Sms(self.msisdn(), to_msisdn, 'from ' + self.name(), *tokens)
         self.log('sending sms to MSISDN', to_msisdn, sms=msg)
         mm = self.dbus.interface(I_SMS)
         mm.SendMessage(to_msisdn, str(msg))
@@ -743,7 +743,7 @@
 
     def call_dial(self, to_msisdn_or_modem):
         if isinstance(to_msisdn_or_modem, Modem):
-            to_msisdn = to_msisdn_or_modem.msisdn
+            to_msisdn = to_msisdn_or_modem.msisdn()
         else:
             to_msisdn = str(to_msisdn_or_modem)
         self.dbg('Dialing:', to_msisdn)
@@ -766,7 +766,7 @@
 
     def call_wait_incoming(self, caller_msisdn_or_modem, timeout=60):
         if isinstance(caller_msisdn_or_modem, Modem):
-            caller_msisdn = caller_msisdn_or_modem.msisdn
+            caller_msisdn = caller_msisdn_or_modem.msisdn()
         else:
             caller_msisdn = str(caller_msisdn_or_modem)
         self.dbg('Waiting for incoming call from:', caller_msisdn)