drm/mode_object: add drm_object_immutable_property_get_value()

drm/mode_object: add drm_object_immutable_property_get_value()

We have a helper to get property values for non-atomic drivers and
another one default property values for atomic drivers. In some cases we
need the ability to get value of immutable property, no matter what kind
of driver it is. Implement new property-related helper,
drm_object_immutable_property_get_value(), which lets the caller to get
the value of the immutable property.

Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patch.msgid.link/20260106-drm-fix-lut-checks-v3-1-f7f979eb73c8@oss.qualcomm.com
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>