Revert "drm/i915/dpt: Make DPT object unshrinkable"

Revert "drm/i915/dpt: Make DPT object unshrinkable"

This reverts commit 51064d471c53dcc8eddd2333c3f1c1d9131ba36c.

Now that we forcefully evict all DPT VMAs during suspend
there should be no problem allowing the shrinker to eat
the DPT objects.

Cc: Brian Geffon <bgeffon@google.com>
Cc: Vidya Srinivas <vidya.srinivas@intel.com>
Closes: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/12965
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241127061117.25622-5-ville.syrjala@linux.intel.com
Acked-by: Brian Geffon <bgeffon@google.com>
Reviewed-by: Vidya Srinivas <vidya.srinivas@intel.com>
Tested-by: Vidya Srinivas <vidya.srinivas@intel.com>