drm/xe: Move xe_ggtt_invalidate out from ggtt->lock

drm/xe: Move xe_ggtt_invalidate out from ggtt->lock

Considering the caller of the GGTT functions should keep the
backing storage alive before the function completes, it's not
necessary to invalidate with the GGTT lock held. This just adds
latency for every user of the GGTT.

Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240306052002.311196-5-matthew.brost@intel.com