mx28evk: Fix warning when CONFIG_ENV_IS_IN_SPI_FLASH is selected

When building a target with CONFIG_ENV_IS_IN_SPI_FLASH the following
warning is seen:

include/configs/mx28evk.h:73:0: warning: "CONFIG_ENV_SIZE" redefined [enabled by default]

Protect the definition of CONFIG_ENV_SIZE to avoid the warning.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
1 file changed