[U-Boot] fit image: boot gzipped ramdisk does not work anymore

[Julius Werner]

> Well, I'm sure you'd find enough FIT images where the uncompression
> might succeed but the target space for decompression is not big enough
> (see bootm_size), would such an error be fixed as well?

I think so? Assuming all the compression algorithms check for an
output buffer overrun (looks like they do), that should also just lead
to a compression error and go into the fallback path.