drm/xe: restrict multi-lrc to VCS/VECS engines

drm/xe: restrict multi-lrc to VCS/VECS engines

Tighten uapi validation to restrict multi-lrc support to VIDEO_DECODE and
VIDEO_ENHANCE engines only. This check should have been in place from the
start, as the driver typically avoids allowing uapi cases that we have
no userspace consumer for.

Additionally, the GuC firmware on ModSched platforms no longer supports
multi-lrc on non-media engines.

V4:
 - use a unified mask for all platforms since engine instance count
   is an independent runtime check (Matt Roper, Matthew Brost)

V3:
 - store a multi-lrc enable class mask in xe->info and populate from
   xe_device_desc in xe_pci.c (Matthew Brost)

V2:
 - correct the typo (Shuicheng)
 - move the check earlier to avoid VM lookup (Shuicheng, Matt Roper)
 - remove the graphics version check (Matt Roper)
 - input more details in the commit info (Matt Roper)

Cc: Shuicheng Lin <shuicheng.lin@intel.com>
Cc: Matt Roper <matthew.d.roper@intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: Xin Wang <x.wang@intel.com>
Reviewed-by: Shuicheng Lin <shuicheng.lin@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patch.msgid.link/20260225022014.45394-1-x.wang@intel.com
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>