mtd: rawnand: oxnas: Unregister all devices on error

On error, the oxnas probe path just frees the device which failed and
aborts the probe, leaving unreleased resources.

Fix this situation by calling mtd_device_unregister()/nand_cleanup()
on these.

Fixes: 66859249 ("mtd: nand: Add OX820 NAND Support")
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20200519130035.1883-38-miquel.raynal@bootlin.com

drivers/mtd/nand/raw/oxnas_nand.c

@@ -82,6 +82,7 @@ static int oxnas_nand_probe(struct platform_device *pdev)
 	struct resource *res;
 	int count = 0;
 	int err = 0;
+	int i;
 
 	/* Allocate memory for the device structure (and zero it) */
 	oxnas = devm_kzalloc(&pdev->dev, sizeof(*oxnas),
@@ -161,6 +162,13 @@ static int oxnas_nand_probe(struct platform_device *pdev)
 	nand_cleanup(chip);
 err_release_child:
 	of_node_put(nand_np);
+
+	for (i = 0; i < oxnas->nchips; i++) {
+		chip = oxnas->chips[i];
+		WARN_ON(mtd_device_unregister(nand_to_mtd(chip)));
+		nand_cleanup(chip);
+	}
+
 err_clk_unprepare:
 	clk_disable_unprepare(oxnas->clk);
 	return err;