uboot-imx

distro: select CMD_ENV_EXISTS

'env exists' is used for scripting in include/config_distro_bootcmd.h
This command is available only when CONFIG_CMD_ENV_EXISTS is enabled.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Alexander Graf <agraf@suse.de>