drm/i915/pvc: Engine definitions for new copy engines

This patch adds the basic definitions needed to support
new copy engines. Also updating the cmd_info to accommodate
new engines, as the engine id's of legacy engines have been
changed.

v2:
 - Add _BCS(n) definition, similar to other engines.  (Tvrtko)
 - Add I915_MAX_BCS definition, similar to other engnes.  (Prathap)
 - Move GVT change to avoid u16 overflow to its own patch.  (Tvrtko)

Original-author: CQ Tang
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Cc: Prathap Kumar Valsan <prathap.kumar.valsan@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: José Roberto de Souza <jose.souza@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220505213812.3979301-9-matthew.d.roper@intel.com