armv8: fsl-layerscape: Set env_loc to ENVL_NOWHERE with CONFIG_ENV_IS_NOWHERE.

ENVL_NOWHERE is dependent on CONFIG_ENV_IS_NOWHERE and not on
CONFIG_CHAIN_OF_TRUST so return ENVL_NOWHERE when CONFIG_ENV_IS_NOWHERE
is enabled

Signed-off-by: Udit Agarwal <udit.agarwal@nxp.com>
Reviewed-by: Prabhakar Kushwaha <prabhakar.kushwaha@nxp.com>