misc: genwqe: fix return value check in genwqe_device_create()

In case of error, the function device_create_with_groups()
returns ERR_PTR() and never returns NULL. The NULL test in
the return value check should be replaced with IS_ERR().
Signed-off-by: NWei Yongjun <yongjun_wei@trendmicro.com.cn>
Acked-by: NFrank Haverkamp <haver@linux.vnet.ibm.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/misc/genwqe/card_dev.c

@@ -1306,8 +1306,8 @@ int genwqe_device_create(struct genwqe_dev *cd)
 					    genwqe_attribute_groups,
 					    GENWQE_DEVNAME "%u_card",
 					    cd->card_idx);
-	if (cd->dev == NULL) {
-		rc = -ENODEV;
+	if (IS_ERR(cd->dev)) {
+		rc = PTR_ERR(cd->dev);
 		goto err_cdev;
 	}