usb: misc: mdm_data_bridge: Clean the driver

Remove support for Interrupt IN data endpoint. Remove appendix of
ZLP after each OUT URB. Add support for required PIDs.
While at it, clean/refactor other parts of the driver.

Change-Id: I307fe2f70b51655cae9b7a529838b94c59d2ec22
Signed-off-by: Ajay Agarwal <ajaya@codeaurora.org>