OPP: Update progress in worker thread.

Use Case:
1) Pair with remote device
2) Transfer file through OPP

Failure:
Less throughput observed for file transfer.

Fix:
OPP throughput was seen very less because of the progress update
from BT Read/Write path. Moved it to worker thread which increased
the throughput.

Change-Id: I767e3619d9e400a35b4a7c9639f6a725bce43d37