drm/xe/migrate: retain CCS aux state for vram -> vram

There is no mention that migrate_copy() will skip copying the CCS aux
state for all types of vram -> vram transfers.  Currently we don't need
such a facility but might be surprising if we ever do.

v2: (Lucas):
  - s/lmem/vram/ in the commit message
  - Tidy up the code a bit; use one emit_copy_ccs()
v3:
  - Reword the commit message

Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Acked-by: Nirmoy Das <nirmoy.das@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>