mtd: nand: docg4: show parent device in sysfs

Fix a bug where parent device symlinks aren't shown in sysfs.

While at it, make use of the default owner value set by mtdcore.
Signed-off-by: Frans Klaver <fransklaver@gmail.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

drivers/mtd/nand/docg4.c

@@ -1316,7 +1316,7 @@ static int __init probe_docg4(struct platform_device *pdev)
 	doc = (struct docg4_priv *) (nand + 1);
 	mtd->priv = nand;
 	nand->priv = doc;
-	mtd->owner = THIS_MODULE;
+	mtd->dev.parent = &pdev->dev;
 	doc->virtadr = virtadr;
 	doc->dev = dev;