engine: Add error message for ifup failure

The patch adds a missing error code from vdsm for
a failure to bring an interface up.

Change-Id: I07adde3368c31319bed48839d089ba3ac48cd424
Bug-Url: https://bugzilla.redhat.com/990938
Signed-off-by: Moti Asayag <masayag@redhat.com>