mtd: nand: make use of nand_set/get_controller_data() helpers

New helpers have been added to avoid directly accessing chip->field. Use
them where appropriate.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
[Brian: fixed a few rebase conflicts]
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
diff --git a/drivers/mtd/nand/nandsim.c b/drivers/mtd/nand/nandsim.c
index 78de37d..f57f461 100644
--- a/drivers/mtd/nand/nandsim.c
+++ b/drivers/mtd/nand/nandsim.c
@@ -667,7 +667,7 @@
 static int init_nandsim(struct mtd_info *mtd)
 {
 	struct nand_chip *chip = mtd_to_nand(mtd);
-	struct nandsim   *ns   = chip->priv;
+	struct nandsim   *ns   = nand_get_controller_data(chip);
 	int i, ret = 0;
 	uint64_t remains;
 	uint64_t next_offset;
@@ -2244,7 +2244,7 @@
 	}
 	nsmtd       = nand_to_mtd(chip);
 	nand        = (struct nandsim *)(chip + 1);
-	chip->priv  = (void *)nand;
+	nand_set_controller_data(chip, (void *)nand);
 
 	/*
 	 * Register simulator's callbacks.