nvmet: fix a width vs precision bug in nvmet_subsys_attr_serial_show()

This was intended to limit the number of characters printed from
"subsys->serial" to NVMET_SN_MAX_SIZE.  But accidentally the width
specifier was used instead of the precision specifier so it only
affects the alignment and not the number of characters printed.

Fixes: f0406481 ("nvmet: fixup buffer overrun in nvmet_subsys_attr_serial()")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

drivers/nvme/target/configfs.c

@@ -1067,7 +1067,7 @@ static ssize_t nvmet_subsys_attr_serial_show(struct config_item *item,
 {
 	struct nvmet_subsys *subsys = to_subsys(item);
 
-	return snprintf(page, PAGE_SIZE, "%*s\n",
+	return snprintf(page, PAGE_SIZE, "%.*s\n",
 			NVMET_SN_MAX_SIZE, subsys->serial);
 }