drm/xe: Name LRC wa after the engine it belongs

This makes it easier when printing the register-save-restore values
to know what is the engine.

Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>