shill: Create and register a Cellular device for each ModemManager.Modem.

BUG=chromium-os:17818
TEST=unit tests

Change-Id: Ic35adf35c8021f4c9689e72ddd03776948d036c1
Reviewed-on: http://gerrit.chromium.org/gerrit/4711
Reviewed-by: Darin Petkov <petkov@chromium.org>
Tested-by: Darin Petkov <petkov@chromium.org>
diff --git a/mock_sockets.h b/mock_sockets.h
index cca5435..a54beef 100644
--- a/mock_sockets.h
+++ b/mock_sockets.h
@@ -16,6 +16,7 @@
   MOCK_METHOD3(Bind,
                int(int sockfd, const struct sockaddr *addr, socklen_t addrlen));
   MOCK_METHOD1(Close, int(int fd));
+  MOCK_METHOD3(Ioctl, int(int d, int request, void *argp));
   MOCK_METHOD4(Send,
                ssize_t(int sockfd, const void *buf, size_t len, int flags));
   MOCK_METHOD6(SendTo, ssize_t(int sockfd,