drm/xe/tests: Drop unused xe_device_fn typedef

We missed to drop it in commit 50680d16 ("drm/xe/tests: remove
unused leftover xe_call_for_each_device()") so drop it now.

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://lore.kernel.org/r/20250613191938.1980-2-michal.wajdeczko@intel.com


Signed-off-by: Matt Roper <matthew.d.roper@intel.com>