drm/xe: Streamline exec queue freeing path

drm/xe: Streamline exec queue freeing path

Ensure exec queue freeing happens at one place, that is in
__xe_exec_queue_free(). It releases q->vm reference also. Set
q->vm before handling extensions as they can potentially reference it.

Signed-off-by: Niranjana Vishwanathapura <niranjana.vishwanathapura@intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240319175947.15890-1-niranjana.vishwanathapura@intel.com