drm/i915/dg2: Add additional tuning settings

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