usb: mdm_bridge: Fix invalid VID/PID registration

The id_table array passed to usb_register was missing a terminating entry.
This caused this driver's probe function to be called whenever any device
was hotplugged.

Change-Id: I290f0e1d609ffc08b740d736dcbe7fcea339fb88
Signed-off-by: Jack Pham <jackp@codeaurora.org>