drm/xe/multi_queue: Set QUEUE_DRAIN_MODE for Multi Queue batches

drm/xe/multi_queue: Set QUEUE_DRAIN_MODE for Multi Queue batches

To properly support soft light restore between batches
being arbitrated at the CFEG, PIPE_CONTROL instructions
have a new bit in the first DW, QUEUE_DRAIN_MODE. When
set, this indicates to the CFEG that it should only
drain the current queue.

Additionally we no longer want to set the CS_STALL bit
for these multi queue queues as this causes the entire
pipeline to stall waiting for completion of the prior
batch, preventing this soft light restore from occurring
between queues in a queue group.

v4: Assert !multi_queue where applicable (Matt Roper)

Bspec: 56551
Signed-off-by: Stuart Summers <stuart.summers@intel.com>
Signed-off-by: Niranjana Vishwanathapura <niranjana.vishwanathapura@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patch.msgid.link/20251211010249.1647839-29-niranjana.vishwanathapura@intel.com