bio_uncompress_inplace() used to potentially need to extend the bio to
be big enough for the uncompressed data, which has become problematic
with multipage bvecs - but, the move extent path actually already
allocated the bios to be big enough for the uncompressed data.

The promote path needed to be fixed, though.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>