net: phy: suspend phydev when going to HALTED

When phydev is going to HALTED state, we can try to suspend it to
safe more power. phy_suspend helper will check if PHY can be suspended,
so just call it when entering HALTED state.

Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Acked-by: Mugunthan V N <mugunthanvnm@ti.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>