Comment 4 for bug 1057646

Just talked to Ricardo, and the answer is yes, we should be able to chain boot uefi from u-boot, although Wookie pointed out that this would cause problems on VExpress when we're security checking, because uefi will complain if it is not the first thing to load.

However, as Ricardo said, just for now all we need to do is add the --bootloader u-boot, which will keep everything stable. I'll implement accordingly.