block: remove zone append special casing from the direct I/O path

This code is unused, and all future zoned file systems should follow
the btrfs lead of splitting the bios themselves to the zoned limits
in the I/O submission handler, because if they didn't they would be
hit by commit ed9832bc ("block: introduce folio awareness and add
a bigger size from folio") breaking this code when the zone append
limit (that is usually the max_hw_sectors limit) is smaller than the
largest possible folio size.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Link: https://lore.kernel.org/r/20241030051859.280923-2-hch@lst.de


Signed-off-by: Jens Axboe <axboe@kernel.dk>