[U-Boot] CONFIG_ENV_ADDR vs CONFIG_ENV_OFFSET

[Adam Ford]

A significant number of omap3 boards use CONFIG_ENV_ADDR and
CONFIG_ENV_OFFSET together.

When CONFIG_ENV_IS_IN_FLASH is defined, environment.h appears to
define CONFIG_ENV_ADDR as CONFIG_SYS_FLASH_BASE + CONFIG_ENV_OFFSET if
CONFIG_ENV_ADDR is not defined, so it assumes that CONFIG_ENV_OFFSET
is defined.

It then tries to define CONFIG_ENV_OFFSET  as CONFIG_ENV_ADDR -
CONFIG_SYS_FLASH_BASE if CONFIG_ENV_OFFSET is not defined, so it
assumes that CONFIG_ENV_ADDR is defined, the finally there is an error
case only when neither are defined.

Since it seems like these should be two different values, can/should
we remove one of them when they are both set to the same value?  Is
one preferred over another?

MTD parts shows the u-boot-env listed as an offset into NAND, so using
CONFIG_ENV_OFFSET would be somewhat consistent to me.

adam