btrfs: zoned: call blkdev_zone_mgmt in nofs scope

Add a memalloc_nofs scope around all calls to blkdev_zone_mgmt(). This
allows us to further get rid of the GFP_NOFS argument for
blkdev_zone_mgmt().

Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: David Sterba <dsterba@suse.com>
Link: https://lore.kernel.org/r/20240128-zonefs_nofs-v3-3-ae3b7c8def61@wdc.com


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