if this function is called in the RAM, we won't be able to
continue start sequence.
It brakes boot over JTAG use case.

Signed-off-by: Oleksij Rempel <linux@rempel-privat.de>
Cc: Yegor Yefremov <yegorslists@googlemail.com>
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>