btrfs: zoned: fix missing endianness conversion in sb_write_pointer

generation is an on-disk __le64 value, so use btrfs_super_generation to
convert it to host endian before comparing it.

Fixes: 1265925 ("btrfs: implement log-structured superblock for ZONED mode")
CC: stable@vger.kernel.org # 5.15+
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Author: Christoph Hellwig

fs/btrfs/zoned.c

@@ -134,7 +134,8 @@ static int sb_write_pointer(struct block_device *bdev, struct blk_zone *zones,
 			super[i] = page_address(page[i]);
 		}
 
-		if (super[0]->generation > super[1]->generation)
+		if (btrfs_super_generation(super[0]) >
+		    btrfs_super_generation(super[1]))
 			sector = zones[1].start;
 		else
 			sector = zones[0].start;