PPv2's XLGMAC can wait for 3 idle frames before triggering a link up
event. This can cause the link to be stuck low when there's traffic on
the interface, so disable this feature.

Fixes: 4bb04326 ("net: mvpp2: phylink support")
Signed-off-by: NMaxime Chevallier <maxime.chevallier@bootlin.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>