net: dsa: microchip: ksz9477: split half-duplex monitoring function

In order to respect the 80 columns limit, split the half-duplex
monitoring function in two.

This is just a styling change, no functional change.

Signed-off-by: Enguerrand de Ribaucourt <enguerrand.de-ribaucourt@savoirfairelinux.com>
Acked-by: Arun Ramadoss <arun.ramadoss@microchip.com>
Signed-off-by: David S. Miller <davem@davemloft.net>