drm/xe/vm: Fix error handling in xe_vm_query_vmas_attrs_ioctl()

drm/xe/vm: Fix error handling in xe_vm_query_vmas_attrs_ioctl()

copy_to_user() returns the number of bytes not copied on failure, not a
negative error code. Update the logic to return -EFAULT instead of the
number of bytes to correctly signal the error.

Fixes: 418807860e94 ("drm/xe/uapi: Add UAPI for querying VMA count and memory attributes")
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/20250828104933.3839825-3-himal.prasad.ghimiray@intel.com
Signed-off-by: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>