[U-Boot] macb: get mac address from environment

[Andrzej Wolski <awolski@poczta.fm>]

>>>> This fix macb driver broken by commit
>>>> 56b555a644f3cbb1b3929cb52b61d3ce483885f5
>>> what exactly broke ?  drivers that are ported to NET_MULTI should *not*
>>> be getting the mac from the environment.  and from what i can see, the
>>> macb driver is properly supporting the NET_MULTI setup.
>>>
>>> looks to me like the existing code is correct and your new proposed code
>>> is not
>> Hmm. Since pointed commit Ethernet just stopped to work, at least on my
>> board similar to SAM9260EK. Maybe someone else can confirm it?
>>
>> Moreover, since that patch, when ethaddr is not set in the environment,
>> and I set it from command line, I get this while trying to ping:
>>
>> U-Boot> ping 192.168.2.1
>> macb0: link up, 100Mbps full-duplex (lpa: 0x45e1)
>> *** ERROR: `ethaddr' not set
>> macb0: link up, 100Mbps full-duplex (lpa: 0x45e1)
>> ping failed; host 192.168.2.1 is not alive
> 
> do you have CONFIG_NET_MULTI defined ?  if not, your board needs to switch 
> over to it.
> -mike

I use configuration for at91sam9260ek board already present in U-Boot 
and CONFIG_NET_MULTI is defined there.

Andrzej