fs: reformat the statx definition

The comments after the declaration are becoming rather unreadable with
long enough comments.  Move them into lines of their own.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20250109083109.1441561-2-hch@lst.de


Reviewed-by: John Garry <john.g.garry@oracle.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>