Recovery when uEnv.txt has the wrong dtb= value

[Jason Kridner]

I've been looking for a little while to find the smallest thing I can type into the u-boot prompt to boot when I put the wrong value into "dtb=" within the uEnv.txt file.

Here's what I decided so far:

setenv uname_boot_bak "${uname_boot}"
setenv uname_boot "setenv fdtfile am335x-boneblack.dtb; run uname_boot_bak"

Anybody have a better one?