engine: Remove redundant message in UpdateVmInterfaceCommand.canDoAction

Remove redundant ACTION_TYPE_FAILED_VM_NOT_EXIST message in
UpdateVmInterfaceCommand.canDoAction method.

Change-Id: I381de1d18f5f094fc1c5d12e06949141d045f525
Signed-off-by: Yevgeny Zaspitsky <yzaspits@redhat.com>