eXMeritus HWW-1U-1A: Minor environment variable tweaks

eXMeritus HWW-1U-1A: Minor environment variable tweaks

Most of the ethernet connections are internal links with specialized
hardware and are not useful for "dhcp" or general-purpose networking;
U-Boot should not be cycling through them.  Force the primary external
network interface in "ethprime" and disable the interface cycling with
"ethrotate=no".

Additionally, the environment variable "preboot" has its own config
option and means something entirely different from what the HWW-1U-1A
variable was intended for.  Rename the board variable to "setbootargs"
to avoid potential confusion.

Finally, fix an incorrect address for the kernel in FLASH memory.

Signed-off-by: Kyle Moffett <[email protected]>
Cc: Andy Fleming <[email protected]>
Signed-off-by: Kumar Gala <[email protected]>