net: phy: Add state machine state transitions debug prints

It can be useful to debug the PHY state machine, add dynamic debug
prints of the old and new PHY devices state under a friendly format.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --cc drivers/net/phy/phy.c
Simple merge