Catch up to ModemManager API change - StateChanged is now iiu, not uuu.

BUG=None (but fixes build)
TEST=emerge shill

Change-Id: Id41d25f09061222790e1b84e70ac769b04049c11
Reviewed-on: https://gerrit.chromium.org/gerrit/19369
Reviewed-by: David Rochberg <rochberg@chromium.org>
Tested-by: Nathan J. Williams <njw@chromium.org>
Commit-Ready: Nathan J. Williams <njw@chromium.org>
diff --git a/mm1_modem_proxy.h b/mm1_modem_proxy.h
index f7da74d..e5cee73 100644
--- a/mm1_modem_proxy.h
+++ b/mm1_modem_proxy.h
@@ -104,8 +104,8 @@
    private:
     // Signal callbacks inherited from Proxy
     // handle signals
-    void StateChanged(const uint32_t &old,
-                      const uint32_t &_new,
+    void StateChanged(const int32_t &old,
+                      const int32_t &_new,
                       const uint32_t &reason);
 
     // Method callbacks inherited from