[U-Boot] u-boot.dtb vs. dts/dt.dtb output filename, also O= vs BUILD_DIR=

[Stephen Warren <swarren@wwwdotorg.org>]

Masahiro,

Prior the to kbuild conversion, U-Boot used to produce file u-boot.dtb
in the root of the object tree. Now it doesn't, but I think puts the
same file in dts/dt.dtb instead. Was this a deliberate change?

We have some flashing utilities that build U-Boot, then copy this result
file. This utility no longer works because the file it's looking for no
longer exists. I'd rather fix the U-Boot build process so its output
filenames don't change, than fix the utility to look for a variety of
different output filenames. Are you OK with a patch reverting the output
filename change?

Related, I also found that pre-Kbuild, I could "make BUILD_DIR=...", but
now I have to "make O=...". That's also an external change in behaviour.
Was that intentional?