fs/buffer fs/mpage: remove large folio restriction

Now that buffer-heads has been converted over to support large folios
we can remove the built-in VM_BUG_ON_FOLIO() checks which prevents
their use.

Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Link: https://lore.kernel.org/r/20250221223823.1680616-6-mcgrof@kernel.org


Reviewed-by: John Garry <john.g.garry@oracle.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>