[U-Boot] [PATCH] net/eth.c: fix eth_write_hwaddr() to use dev->enetaddr as fall back

[Zach Sadecki]

This patch will also fix a problem with mx28 boards that are depending 
on the OCOTP bits to set the MAC address (like the Denx m28 board).  Now 
it simply fails with a "Warning: failed to set MAC address" if there's 
no environment variable instead of using the OCOTP bits like it should.  
This patch will fix that.