mtd: rawnand: bcm47xx: Stop using nand_release()

This helper is not very useful and very often people get confused:
they use nand_release() instead of nand_cleanup().

Let's stop using nand_release() by calling mtd_device_unregister() and
nand_cleanup() directly.
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20200519130035.1883-4-miquel.raynal@bootlin.com

drivers/mtd/nand/raw/bcm47xxnflash/main.c

@@ -60,8 +60,12 @@ static int bcm47xxnflash_probe(struct platform_device *pdev)
 static int bcm47xxnflash_remove(struct platform_device *pdev)
 {
 	struct bcm47xxnflash *nflash = platform_get_drvdata(pdev);
+	struct nand_chip *chip = &nflash->nand_chip;
+	int ret;
 
-	nand_release(&nflash->nand_chip);
+	ret = mtd_device_unregister(nand_to_mtd(chip));
+	WARN_ON(ret);
+	nand_cleanup(chip);
 
 	return 0;
 }