drm/i915/ats-m: Add thread execution tuning setting

On client DG2 platforms, optimal performance is achieved with the
hardware's default "age based" thread execution setting.  However on
ATS-M, switching this to "round robin after dependencies" provides
better performance.  We'll add a new "tuning" feature flag to the ATS-M
device info to enable/disable this setting.

Bspec: 68331
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Matt Atwood <matthew.s.atwood@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220826212718.409948-1-matthew.d.roper@intel.com