sh_eth: make 'link' field of 'struct sh_eth_private' *int*

The 'link' field of 'struct sh_eth_private' has type 'enum phy_state' while the
'link' field of 'struct phy_device' is merely *int* (having values 0 and 1) and
the former field gets assigned from the latter. Make the field match, getting
rid of incorrectly used PHY_DOWN value in assignments/comparisons.

Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: David S. Miller <davem@davemloft.net>