drm/xe/display: Make display suspend/resume work on discrete

We should unpin before evicting all memory, and repin after GT resume.
This way, we preserve the contents of the framebuffers, and won't hang
on resume due to migration engine not being restored yet.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Fixes: dd08ebf6 ("drm/xe: Introduce a new DRM driver for Intel GPUs")
Cc: stable@vger.kernel.org # v6.8+
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240806105044.596842-3-maarten.lankhorst@linux.intel.com


Signed-off-by: Maarten Lankhorst,,, <maarten.lankhorst@linux.intel.com>