drm/xe: Normalize pte/pde encoding

drm/xe: Normalize pte/pde encoding

Split functions that do only part of the pde/pte encoding and that can
be called by the different places. This normalizes how pde/pte are
encoded so they can be moved elsewhere in a subsequent change.

xe_pte_encode() was calling __pte_encode() with a NULL vma, which is the
opposite of what xe_pt_stage_bind_entry() does. Stop passing a NULL vma
and just split another function that deals with a vma rather than a bo.

Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://lore.kernel.org/r/20230927193902.2849159-2-lucas.demarchi@intel.com
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>