virtio_blk: cleanup zoned device probing

Move reading and checking the zoned model from virtblk_probe_zoned_device
into the caller, leaving only the code to perform the actual setup for
host managed zoned devices in virtblk_probe_zoned_device.

This allows to share the model reading and sharing between builds with
and without CONFIG_BLK_DEV_ZONED, and improve it for the
!CONFIG_BLK_DEV_ZONED case.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20231217165359.604246-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>