USB: mdm_bridge: Fix control bridge suspend

The current code does not abort suspend when there are pending URBs.
They are simply killed during suspend. This may lead to QMI stall.
Add proper checks to ensure that there is no pending Tx/Rx data
during suspend.  Clear the "SUSPENDED" flag in resume only after
taking out all the URBs from "tx_deferred" anchor.

CRs-Fixed: 451414
Change-Id: Icc48afc5eeedcc126d0ab1bec951bde4a53ac165
Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>