nvme-fc: remove ->poll implementation

It's specifically looking for a given request, which we will not be
supporting going forward. Also kill the qla2xxx poll implementation
as that's the only user of the nvme-fc poll, and the now unused
->poll_queue() hook.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: James Smart <jsmart2021@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>