mtd: rawnand: Leave chip->IO_ADDR_{R, W} to NULL when unused

There's no point in poisoning the ->IO_ADDR_{R,W}, a NULL pointer
is just as good to detect unexpected ->IO_ADDR_{R,W} usage.
Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>

drivers/mtd/nand/raw/brcmnand/brcmnand.c

@@ -2270,9 +2270,6 @@ static int brcmnand_init_cs(struct brcmnand_host *host, struct device_node *dn)
 	mtd->owner = THIS_MODULE;
 	mtd->dev.parent = &pdev->dev;
 
-	chip->IO_ADDR_R = (void __iomem *)0xdeadbeef;
-	chip->IO_ADDR_W = (void __iomem *)0xdeadbeef;
-
 	chip->cmd_ctrl = brcmnand_cmd_ctrl;
 	chip->cmdfunc = brcmnand_cmdfunc;
 	chip->waitfunc = brcmnand_waitfunc;

drivers/mtd/nand/raw/socrates_nand.c

@@ -152,10 +152,6 @@ static int socrates_nand_probe(struct platform_device *ofdev)
 	mtd->name = "socrates_nand";
 	mtd->dev.parent = &ofdev->dev;
 
-	/*should never be accessed directly */
-	nand_chip->IO_ADDR_R = (void *)0xdeadbeef;
-	nand_chip->IO_ADDR_W = (void *)0xdeadbeef;
-
 	nand_chip->cmd_ctrl = socrates_nand_cmd_ctrl;
 	nand_chip->read_byte = socrates_nand_read_byte;
 	nand_chip->write_buf = socrates_nand_write_buf;