mips: nand: make use of mtd_to_nand() where appropriate

mtd_to_nand() was recently introduced to avoid direct accesses to the
mtd->priv field. Update all MIPS specific implementations to use this
helper.

Signed-off-by: Boris Brezillon <[e-mail]>
Acked-by: Brian Norris <[e-mail]>
Signed-off-by: Brian Norris <[e-mail]>

arch/mips/alchemy/devboards/db1200.c

···
 static void au1200_nand_cmd_ctrl(struct mtd_info *mtd, int cmd,
 				 unsigned int ctrl)
 {
-	struct nand_chip *this = mtd->priv;
+	struct nand_chip *this = mtd_to_nand(mtd);
 	unsigned long ioaddr = (unsigned long)this->IO_ADDR_W;
 
 	ioaddr &= 0xffffff00;

arch/mips/alchemy/devboards/db1300.c

···
 static void au1300_nand_cmd_ctrl(struct mtd_info *mtd, int cmd,
 				 unsigned int ctrl)
 {
-	struct nand_chip *this = mtd->priv;
+	struct nand_chip *this = mtd_to_nand(mtd);
 	unsigned long ioaddr = (unsigned long)this->IO_ADDR_W;
 
 	ioaddr &= 0xffffff00;

arch/mips/alchemy/devboards/db1550.c

···
 static void au1550_nand_cmd_ctrl(struct mtd_info *mtd, int cmd,
 				 unsigned int ctrl)
 {
-	struct nand_chip *this = mtd->priv;
+	struct nand_chip *this = mtd_to_nand(mtd);
 	unsigned long ioaddr = (unsigned long)this->IO_ADDR_W;
 
 	ioaddr &= 0xffffff00;

arch/mips/pnx833x/common/platform.c

···
 static void
 pnx833x_flash_nand_cmd_ctrl(struct mtd_info *mtd, int cmd, unsigned int ctrl)
 {
-	struct nand_chip *this = mtd->priv;
+	struct nand_chip *this = mtd_to_nand(mtd);
 	unsigned long nandaddr = (unsigned long)this->IO_ADDR_W;
 
 	if (cmd == NAND_CMD_NONE)

arch/mips/rb532/devices.c

···
 
 static void rb532_cmd_ctrl(struct mtd_info *mtd, int cmd, unsigned int ctrl)
 {
-	struct nand_chip *chip = mtd->priv;
+	struct nand_chip *chip = mtd_to_nand(mtd);
 	unsigned char orbits, nandbits;
 
 	if (ctrl & NAND_CTRL_CHANGE) {