mtd: rawnand: marvell: Use correct logic for nand-keep-config

Originally the absence of the marvell,nand-keep-config property caused
the setup_data_interface function to be provided. However when
setup_data_interface was moved into nand_controller_ops the logic was
unintentionally inverted. Update the logic so that only if the
marvell,nand-keep-config property is present the bootloader NAND config
kept.

Cc: stable@vger.kernel.org
Fixes: 7a08dbae ("mtd: rawnand: Move ->setup_data_interface() to nand_controller_ops")
Signed-off-by: Tony O'Brien <tony.obrien@alliedtelesis.co.nz>
Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20220927024728.28447-1-chris.packham@alliedtelesis.co.nz