Documentation: update Ethernet PHY devices binding with 'max-speed'

The 'max-speed' property is optional but defined in the ePAPR
specification and now supported by the Linux Device Tree parsing
infrastructure.

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