mtd: rawnand: stm32_fmc2: 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>
Cc: Christophe Kerello <christophe.kerello@st.com>
Reviewed-by: Christophe Kerello <christophe.kerello@st.com>
Link: https://lore.kernel.org/linux-mtd/20200519130035.1883-53-miquel.raynal@bootlin.com

drivers/mtd/nand/raw/stm32_fmc2_nand.c

@@ -1983,8 +1983,12 @@ static int stm32_fmc2_nfc_remove(struct platform_device *pdev)
 {
 	struct stm32_fmc2_nfc *nfc = platform_get_drvdata(pdev);
 	struct stm32_fmc2_nand *nand = &nfc->nand;
+	struct nand_chip *chip = &nand->chip;
+	int ret;
 
-	nand_release(&nand->chip);
+	ret = mtd_device_unregister(nand_to_mtd(chip));
+	WARN_ON(ret);
+	nand_cleanup(chip);
 
 	if (nfc->dma_ecc_ch)
 		dma_release_channel(nfc->dma_ecc_ch);