When oversubscribing SDMA gangs, a circular deadlock can occur since
gang enqueue is staggered with respect to SDMA engine leader based
on source to destination.
As a result, an enqueued leader may be waiting on a gang item that is
waiting on another enqueued leader or gang item and so on.
To prevent this, first lock the submission to ensure dma status query
and submissions are atomic. Once this is in place, be more stringent
with ganging in that all SDMA engines must be available in order to gang.
Finally, re-enable SDMA ganging by default.
Change-Id: I4511e3487db9d26475b5aece4897f10168cc5322
Jonathan Kim
8f21793a3e