ethernet: mvneta: Use PHY status standard message

Use phy_print_status() to report a change in the PHY status.
The current message is not verbose enough, so this commit improves
it by using the generic status message.

After this change, the kernel reports PHY status down and up events as:

mvneta f1070000.ethernet eth0: Link is Down
mvneta f1070000.ethernet eth0: Link is Up - 1Gbps/Full - flow control rx/tx

Signed-off-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
Signed-off-by: David S. Miller <davem@davemloft.net>