Some additional MMIO tuning settings have appeared in the bspec's
performance tuning guide section.

One of the tuning settings here is also documented as formal workaround
Wa_22012654132 for some steppings of DG2.  However the tuning setting
applies to all DG2 variants and steppings, making it a superset of the
workaround.

v2:
 - Move DRAW_WATERMARK to engine workaround section.  It only moves into
   the engine context on future platforms.  (Lucas)
 - CHICKEN_RASTER_2 needs to be handled as a masked register.  (Lucas)

Bspec: 68331
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Cc: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220816210601.2041572-2-matthew.d.roper@intel.com