Use spinand_to_nand() and spinand_to_mtd() helpers instead of
nanddev_to_mtd() and direct access to spinand structure fields.
Signed-off-by: Mikhail Kshevetskiy <mikhail.kshevetskiy@iopsys.eu>
Reviewed-by: Frieder Schrempf <frieder.schrempf@kontron.de>
Signed-off-by: Michael Trimarchi <michael@amarulasolutions.com>