net: phy: at803x: enable prefer master for 83xx internal phy

From original QCA source code the port was set to prefer master as port
type in 1000BASE-T mode. Apply the same settings also here.

Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>