drm/xe/vm: Skip ufence association for CPU address mirror VMA during MAP

drm/xe/vm: Skip ufence association for CPU address mirror VMA during MAP

The MAP operation for a CPU address mirror VMA does not require ufence
association because such mappings are not GPU-synchronized and do not
participate in GPU job completion signaling.

Remove the unnecessary ufence addition for this case to avoid -EBUSY
failure in check_ufence of unbind ops.

Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Link: https://patch.msgid.link/20251125075628.1182481-6-himal.prasad.ghimiray@intel.com
Signed-off-by: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>