When there are multiple memory backends in use, including the object type
and property name in the error message can help users to locate the error.

Signed-off-by: Haozhong Zhang <haozhong.zhang@intel.com>
Signed-off-by: Zhang Yi <yi.z.zhang@linux.intel.com>
Message-Id: <97d9193875747d8378c05b9e3b3cb39c1b7d2b4e.1546399191.git.yi.z.zhang@linux.intel.com>
Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
[ehabkost: reword commit message]
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>