drm/i915/icl: Prepare for more rings

Gen11 will add more VCS and VECS rings so prepare the
infrastructure to support that.

Bspec: 7021

v2: Rebase.
v3: Rebase.
v4: Rebase.
v5: Rebase.
v6:
  - Update for POR changes. (Daniele Ceraolo Spurio)
  - Add provisional guc engine ids - to be checked and confirmed.
v7:
  - Rebased.
  - Added the new ring masks.
  - Added the new HW ids.
v8:
  - Introduce I915_MAX_VCS/VECS to avoid magic numbers (Michal)

v9: increase MAX_ENGINE_INSTANCE to 3

Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Oscar Mateo <oscar.mateo@intel.com>
Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Reviewed-by: Oscar Mateo <oscar.mateo@intel.com>
Signed-off-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180228101153.7224-1-mika.kuoppala@linux.intel.com