drm/xe: Fix indentation in xe_zap_ptes_in_madvise_range

drm/xe: Fix indentation in xe_zap_ptes_in_madvise_range

Fix misleading indentation around WRITE_ONCE in pte zap loop.
No functional change intended.

Fixes: ada7486c5668 ("drm/xe: Implement madvise ioctl for xe")
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Tejas Upadhyay <tejas.upadhyay@intel.com>
Link: https://lore.kernel.org/r/20250828104933.3839825-2-himal.prasad.ghimiray@intel.com
Signed-off-by: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>