dfc: Enable TX when grant is received

When TX is OFF from one client but a positive grant is received
from another client, treat it as TX ON. This is to prevent data
stall due to a race condition that TX status from different transports
could arrive out-of-order.

Change-Id: Id257b79569390a47f863d713e89b2c868561af7b
Acked-by: Weiyi Chen <weiyic@qti.qualcomm.com>
Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>