arm64: mvebu: armada-8k: support environment in SD/eMMC

Detect the SD/eMMC boot device at run-time. Load the environment from
the boot deice, as well as save to it.

Leave the environment offset the same as in the SPI flash.

Make SD/eMMC 0 the default environment device when the boot device is
not detected.

Cc: Konstantin Porotchkin <kostap@marvell.com>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Stefan Roese <sr@denx.de>
2 files changed