[U-Boot] Initial environment variables

[Ron Madrid]

When I submitted patches for my new board SIMPC8313 I recall being told that
I had inappropriately initialized some of my environment variables.  Most
specifically I am interested in having default serverip, ipaddr, and ethaddr
environment variables.  Is this most appropriately done with a specific
#define (such as #define CONFIG_SERVERIP) or within #define
CONFIG_EXTRA_ENV_SETTINGS?

Thanks for the help.

Ron