net: phy: do not print dump stack if device was removed

In case phy_state_machine() works on top of USB device, we can get -ENODEV
at any point. So, be less noisy if device was removed.

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>