3535de4 virNetDevBandwidthPlug: Update function description

Authored and Committed by mprivozn 9 years ago
    virNetDevBandwidthPlug: Update function description
    
    The comment is describing arguments passed to the function.
    However, there's no @ifmac argument. In 955af4d4 it was replaced
    with @ifmac_ptr.  Unfortunately, the comment wasn't updated.
    
    Signed-off-by: Michal Privoznik <mprivozn@redhat.com>