linux-imx

mtd: nand: add helpers to access ->priv

Add two helpers to access the field reserved for private controller data.
This makes it clearer what this field is reserved for and ease future
refactoring.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>