[U-Boot] Defer net initialization

[Alexander Stein]

Hello,

during board setup the ethernet is configured including the PHY. This takes an 
amount of time even if the cable is plugged in. It takes even more time of the 
initialization runs into a timeout if no cable is put in.
Is there a possibility to defer the net initialization up to that point where 
the first net access is done, e.g. tftp command and leave the net 
uninitialized during normal startup using fsload and bootm.

Best regards
Alexander