drm/xe/rtp: Replace XE_WARN_ON

Now that rule_matches() always has an xe pointer, replace the XE_WARN_ON
with the more appropriate drm_warn().

Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://lore.kernel.org/r/20230526164358.86393-4-lucas.demarchi@intel.com


Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>