libnvdimm-btt: Delete an unnecessary check before the function call "__nd_device_register"

The __nd_device_register() function tests whether its argument is NULL
and then returns immediately. Thus the test around the call is not needed.

This issue was detected by using the Coccinelle software.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

drivers/nvdimm/btt_devs.c

@@ -198,8 +198,7 @@ struct device *nd_btt_create(struct nd_region *nd_region)
 {
 	struct device *dev = __nd_btt_create(nd_region, 0, NULL, NULL);
 
-	if (dev)
-		__nd_device_register(dev);
+	__nd_device_register(dev);
 	return dev;
 }