The old code basically said it was going to use some particular blob
without knowing whether it could successfully do so, then it would invoke
the function to do that and return its status. If it failed, you were
done, even if other blobs might be available. Now the code attempts to use
some particular blob and if that succeeds it says so and returns success,
otherwise it moves on to try another potential blob.
One specific problem this solves is when u-boot sets an fdtaddr variable
to point to some memory address, then doesn't actually load a blob at
that address. Now the header check will fail, and the code will move
on to the fallback dtb compiled into the kernel (if any).
d000dd2f86