Uses an outdated atf branch

Upstream (Debian) is on 2.2 already while the fork we're using is 2.0 based as far as i can tell.

$ git describe HEAD
v2.0-201-g2208126b

@angus.ainslie since you brought in u-boot (uboot-imx#11 (closed), uboot-imx#22 (closed)) and atf: is updating these somewhere on your list?

It is but currently there are many more high priority items.

As the u-boot code is working for our currently use cases this is a low priority item for me. Once we revisit suspend is when I'll likely have a look at ATF again.

thanks for the update!

mentioned in commit guido.gunther/uboot-imx@7931f2b5

mentioned in commit guido.gunther/uboot-imx@32b53f0a