qemu: Add missing goto error in qemuRestoreCgroupState
    
    Commit af2a1f05 tried clearly separating each condition in
    qemuRestoreCgroupState() for the sake of readability, however somehow
    one condition body was missing.  That means that the body of the next
    condition got executed only if both of there were true, which is
    impossible, thus resulting in a dead code and a logic error.
    
    Signed-off-by: Martin Kletzander <mkletzan@redhat.com>