drm/xe: Rename ___xe_bo_create_locked()

Don't start external function names with underscores.
Rename to xe_bo_init_locked().

Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Link: https://lore.kernel.org/r/20250908101246.65025-10-thomas.hellstrom@linux.intel.com