media: s5p-mfc: Add checking to s5p_mfc_probe().

If of_device_get_match_data() return NULL,
then null pointer dereference occurs in  s5p_mfc_init_pm().
The patch adds checking if dev->variant is NULL.

Found by Linux Driver Verification project (linuxtesting.org).
Signed-off-by: NNadezda Lutovinova <lutovinova@ispras.ru>
Signed-off-by: NHans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: NMauro Carvalho Chehab <mchehab+huawei@kernel.org>

drivers/media/platform/s5p-mfc/s5p_mfc.c

@@ -1288,6 +1288,10 @@ static int s5p_mfc_probe(struct platform_device *pdev)
 	}
 
 	dev->variant = of_device_get_match_data(&pdev->dev);
+	if (!dev->variant) {
+		dev_err(&pdev->dev, "Failed to get device MFC hardware variant information\n");
+		return -ENOENT;
+	}
 
 	dev->regs_base = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(dev->regs_base))