usb: mdm_bridge: Free driver data structure memory in correct order

mdm bridge driver allocates driver data structure for dial up network
and RMNET interface in the order interface probe is called. Driver frees
the data structure memory for control channel in reverse order in
interface disconnect. This causes the usb core driver to access freed
memory(freed during dial up network interface unbind) for control
channel when it unbinds RMNET interface. Hence allocate and free data
structure memory for control channel in the same order in which it was
allocated.

CRs-Fixed: 394951
Change-Id: Ic399c123253fcee46895e3b0b749dcd0fe43d99d
Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>