net: ethernet: broadcom: Fix build errors

Commit 7f854420 ("phy: Add API for {un}registering an mdio device to
a bus") introduces an API to access mii_bus structures, but missed to
update the sb1250 driver. This results in the following build error.

drivers/net/ethernet/broadcom/sb1250-mac.c: In function 'sbmac_mii_probe':
drivers/net/ethernet/broadcom/sb1250-mac.c:2360:24: error:
	'struct mii_bus' has no member named 'phy_map'

Use phy_find_first() instead of open coding it.

Commit 2220943a ("phy: Centralise print about attached phy") introduces
the following build error.

drivers/net/ethernet/broadcom/sb1250-mac.c: In function 'sbmac_mii_probe':
drivers/net/ethernet/broadcom/sb1250-mac.c:2383:20: error: 'phydev' undeclared

Fixes: 7f854420 ("phy: Add API for {un}registering an mdio device to a bus")
Fixes: 2220943a ("phy: Centralise print about attached phy")
Cc: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>