drm/xe: Drop ggtt invalidate from display code

drm/xe: Drop ggtt invalidate from display code

Only buffers mapped in the GGTT used by the GuC require an invalidation.
Display buffers do not require an invalidation. Delete the invalidatio
from display code and make invalidation a static function in xe_ggtt.c.

Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240306052002.311196-3-matthew.brost@intel.com