phylib: fix phy name example in documentation

All MDIO bus drivers currently name bus with "%x" format.
There is one exception where mv643xx_eth driver is using "%d".
Phy address on the bus uses format "%02x".

Fixing phy name example to match all real life MDIO drivers.

Signed-off-by: Paulius Zaleckas <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

Documentation/networking/phy.txt

···
    static void adjust_link(struct net_device *dev);
  
  Next, you need to know the device name of the PHY connected to this device. 
- The name will look something like, "phy0:0", where the first number is the
+ The name will look something like, "0:00", where the first number is the
  bus id, and the second is the PHY's address on that bus.  Typically,
  the bus is responsible for making its ID unique.