drm/xe/migrate: ignore CCS for kernel objects

For kernel BOs we don't clear the CCS state on creation, therefore we
should be careful to ignore it when copying pages. In a future patch we
opt for using the copy path here for kernel BOs, so this now needs to be
considered.

v2:
 - Drop bogus asserts (CI)

Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Satyanarayana K V P <satyanarayana.k.v.p@intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Satyanarayana K V P <satyanarayana.k.v.p@intel.com>
Link: https://lore.kernel.org/r/20250403102440.266113-12-matthew.auld@intel.com