Revert "nvme: add support for the Write Zeroes command"

Revert "nvme: add support for the Write Zeroes command"

This reverts commit 250c7bb1f0866ceb2cae829c954c360a504cd4a4.

This causes bootup problems for me both on my laptop and my desktop.
What they have in common is that they have NVMe disks with dm-crypt, but
it's not the same controller, so it's not controller-specific.

Jens does not see it on his machine (also NVMe), so it's presumably
something that triggers just on bootup.  Possibly related to dm-crypt
and the fact that I mark my luks volume with "allow-discards" in
/etc/crypttab.

It's 100% repeatable for me, which made it fairly straightforward to
bisect the problem to this commit. Small mercies.

So we don't know what the reason is yet, but the revert is needed to get
things going again.

Acked-by: Jens Axboe <axboe@fb.com>
Cc: Chaitanya Kulkarni <chaitanya.kulkarni@hgst.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>