btrfs: do not abort transaction on failure to update log root

When syncing a log, if we fail to update a log root in the log root tree,
we are aborting the transaction if the failure was not -ENOSPC. This is
excessive because there is a chance that a transaction commit can succeed,
and therefore avoid to turn the filesystem into RO mode. All we need to be
careful about is to mark the log for a full commit, which we already do,
to make sure no one commits a super block pointing to an outdated log root
tree.

So don't abort the transaction if we fail to update a log root in the log
root tree, and log an error if the failure is not -ENOSPC, so that it does
not go completely unnoticed.

CC: stable@vger.kernel.org # 6.0+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>