drm/xe: Fixup unwind on VM ops errors

Remap ops have 3 parts: unmap, prev, and next. The commit step can fail
on any of these. Add a flag for each to these so the unwind is only done
the steps that have been committed.

v2: (Rodrigo) Use bit macros

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