media: s5p-mfc: Improve a size determination in s5p_mfc_alloc_memdev()

Replace the specification of a data structure by a pointer dereference
as the parameter for the operator "sizeof" to make the corresponding size
determination a bit safer according to the Linux coding style convention.

This issue was detected by using the Coccinelle software.
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

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

@@ -1083,7 +1083,7 @@ static struct device *s5p_mfc_alloc_memdev(struct device *dev,
 	struct device *child;
 	int ret;
 
-	child = devm_kzalloc(dev, sizeof(struct device), GFP_KERNEL);
+	child = devm_kzalloc(dev, sizeof(*child), GFP_KERNEL);
 	if (!child)
 		return NULL;