fence->ctx may be stale memory when trace_xe_hw_fence_free is called
resuling UAF bug when deriving the device name. This tracepoint is not
all that useful, so just drop it.

Fixes: 501c4255 ("drm/xe/trace: Print device_id in xe_trace events")
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Cc: Gustavo Sousa <gustavo.sousa@intel.com>
Cc: Radhakrishna Sripada <radhakrishna.sripada@intel.com>
Cc: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240708211008.956384-1-matthew.brost@intel.com