x86/platform/mellanox: Fix return value check in mlxplat_init()

In case of error, the function platform_device_register_simple()
returns ERR_PTR() and never returns NULL. The NULL test in the
return value check must therefor be replaced with IS_ERR().
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Acked-by: Vadim Pasternak <vadimp@mellanox.com>
Cc: platform-driver-x86@vger.kernel.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/x86/platform/mellanox/mlx-platform.c

@@ -200,8 +200,8 @@ static int __init mlxplat_init(void)
 					mlxplat_lpc_resources,
 					ARRAY_SIZE(mlxplat_lpc_resources));
 
-	if (!mlxplat_dev)
-		return -ENOMEM;
+	if (IS_ERR(mlxplat_dev))
+		return PTR_ERR(mlxplat_dev);
 
 	priv = devm_kzalloc(&mlxplat_dev->dev, sizeof(struct mlxplat_priv),
 			    GFP_KERNEL);