drm/xe/sa: Always call drm_suballoc_manager_fini()

After successful call to drm_suballoc_manager_init() we should
make sure to call drm_suballoc_manager_fini() as it may include
some cleanup code even if we didn't start using it for real.

As we can abort init() early due to kvzalloc() failure, we should
either explicitly call drm_suballoc_manager_fini() or, even better,
postpone drm_suballoc_manager_init() once we finish all other
preparation steps, so we can rely on fini() that will do cleanup.

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241220194205.995-2-michal.wajdeczko@intel.com