By default on module load, 2 ifb interfaces are created and typically
remain unused, cluttering 'ip link' outputs and generally confusing
things.  sqm-scripts for example, creates its own ifb interface/s
instead of using these 2 defaults ifbs.

Tell the ifb module to not create any default ifbs on load via the
numifbs parameter.

Signed-off-by: Kevin Darbyshire-Bryant <ldir@darbyshire-bryant.me.uk>