mx7_common: Share configs to skip low level init

Share configs in mx7 to skip low level init if we are in the case where
OPTEE is loaded already (maybe by ARM Trusted Firmware) and that most of
the low level initialization is already done and that we may/should skip
it doing them here.

Fix the definition detection with size detection to decide whether to skip
it.

Signed-off-by: Jun Nie <jun.nie@linaro.org>
Reviewed-by: Fabio Estevam <festevam@gmail.com>