[U-Boot] Disable features

[Derek Ou]

Hi,
> Is existing a way to globally disable some features such as ethernet
> or Nand support, instead of doing it for a specific board?
>   
Other than recompiling, is it possible to disable Ethernet through 
environment settings?  At our
work, we often need Ethernet only during development, manufacturing and 
troubleshooting.  So
we put the Ethernet chip on the test fixture instead of the final 
board.  However, compiling in
Ethernet slow down the booting process.  So it will be great if Ethernet 
can be disabled and
enabled by flipping an environment setting.

Derek