drm/xe: Only set VM->asid for platforms that support a ASID

This will help with TLB invalidation as the ASID in TLB invalidate
should be zero for platforms that do not support a ASID.

Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Niranjana Vishwanathapura <niranjana.vishwanathapura@intel.com>