dfc: add stall recovery timer

Add watchdog timer to recover potential data stall when data is
not going to the expected DRB and no DFC indication is received.

Change-Id: Iaa4b4814967cf9400c36115a083922376d23928d
Acked-by: Weiyi Chen <weiyic@qti.qualcomm.com>
Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>