null_blk: don't suppress partitioning information

This manually reverts commit 27290b469051 ("null_blk: suppress invalid
partition info").  The message in that commit log can't appearch as
the flag is never checked during probing, and there is no good reason
to treat null_blk special in /proc/partitions.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211122130625.1136848-9-hch@lst.deSigned-off-by: Jens Axboe <axboe@kernel.dk>

drivers/block/null_blk/main.c

@@ -1850,7 +1850,7 @@ static int null_gendisk_register(struct nullb *nullb)
 
 	set_capacity(disk, size);
 
-	disk->flags |= GENHD_FL_EXT_DEVT | GENHD_FL_SUPPRESS_PARTITION_INFO;
+	disk->flags |= GENHD_FL_EXT_DEVT;
 	disk->major		= null_major;
 	disk->first_minor	= nullb->index;
 	disk->minors		= 1;