mtd: rawnand: davinci: Do not use extra dereferencing

When the nand_chip structure is already available, there is no need to
dereference it through the info pointer. Use the chip pointer directly
in this case.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20201113124045.32743-1-miquel.raynal@bootlin.com