qdev: Rename qdev_get_prop_ptr() to object_field_prop_ptr()

qdev: Rename qdev_get_prop_ptr() to object_field_prop_ptr()

The function will be moved to common QOM code, as it is not
specific to TYPE_DEVICE anymore.

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Acked-by: Paul Durrant <paul@xen.org>
Message-Id: <20201211220529.2290218-31-ehabkost@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>