mtd: rawnand: ingenic: Fix the RB gpio active-high property on qi, lb60

The rb-gpios semantics was undocumented and qi,lb60 (along with the
ingenic driver) got it wrong. The active state encodes the NAND ready
state, which is high level. Since there's no signal inverter on this
board, it should be active-high. Let's fix that here for older DTs so
we can re-use the generic nand_gpio_waitrdy() helper, and be consistent
with what other drivers do.

Suggested-by: Paul Cercueil <paul@crapouillou.net>
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20200519232454.374081-3-boris.brezillon@collabora.com