net: ethernet: fs_enet: use macros for speed and duplex values

The PHY speed and duplex should be manipulated using the SPEED_XXX and
DUPLEX_XXX macros available. Use it in the fcc, fec and scc MAC for
fs_enet.

Acked-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Signed-off-by: David S. Miller <davem@davemloft.net>