Instead of sending each argument of struct compressed_bio, send
the compressed_bio itself.

Also by having struct compressed_bio in btrfs_decompress_bio()
it would help tracing.
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>