drm/xe/hw_engine: Fix double-free of managed BO in error path

drm/xe/hw_engine: Fix double-free of managed BO in error path

The error path in hw_engine_init() explicitly frees a BO allocated
with xe_managed_bo_create_pin_map() via xe_bo_unpin_map_no_vm().
Since the managed BO already has a devm cleanup action registered,
this causes a double-free when devm unwinds during probe failure.

Remove the explicit free and let devm handle it, consistent with
all other xe_managed_bo_create_pin_map() callers.

Fixes: 0e1a47fcabc8 ("drm/xe: Add a helper for DRM device-lifetime BO create")
Assisted-by: Claude:claude-opus-4.6
Reviewed-by: Zongyao Bai <zongyao.bai@intel.com>
Link: https://patch.msgid.link/20260626210631.3887291-1-shuicheng.lin@intel.com
Signed-off-by: Shuicheng Lin <shuicheng.lin@intel.com>