net: mvneta: fix build errors when linux/phy*.h is removed from net/dsa.h

drivers/net/ethernet/marvell/mvneta.c:2694:26: error: storage size of 'status' isn't known
drivers/net/ethernet/marvell/mvneta.c:2695:26: error: storage size of 'changed' isn't known
drivers/net/ethernet/marvell/mvneta.c:2695:9: error: variable 'changed' has initializer but incomplete type
drivers/net/ethernet/marvell/mvneta.c:2709:2: error: implicit declaration of function 'fixed_phy_update_state' [-Werror=implicit-function-declaration]

Add linux/phy_fixed.h to mvneta.c

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Acked-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: David S. Miller <davem@davemloft.net>