arm/km: add CONFIG_KM_BOARD_EXTRA_ENV to default environment

This is needed for board specific additional environment variables.
E.g. the mgcoge3un has this additional "waitforne" variable.

Signed-off-by: Holger Brunck <holger.brunck@keymile.com>
Acked-by: Valentin Longchamp <valentin.longchamp@keymile.com>
1 file changed