nvme: fix parameter check in nvme_fault_inject_init()

Make IS_ERR() judge the debugfs_create_dir() function return.
Signed-off-by: Minjie Du <duminjie@vivo.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <kbusch@kernel.org>

drivers/nvme/host/fault_inject.c

@@ -27,7 +27,7 @@ void nvme_fault_inject_init(struct nvme_fault_inject *fault_inj,
 
 	/* create debugfs directory and attribute */
 	parent = debugfs_create_dir(dev_name, NULL);
-	if (!parent) {
+	if (IS_ERR(parent)) {
 		pr_warn("%s: failed to create debugfs directory\n", dev_name);
 		return;
 	}