mfd: rohm-bd718x7: Drop useless mask_invert flag on irqchip

Setting mask_invert to false is pointless because that's the
default. The flag is also deprecated, so drop it.

Signed-off-by: Aidan MacDonald <aidanmacdonald.0x0@gmail.com>
Reviewed-by: Matti Vaittinen <mazziesaccount@gmail.com>
Signed-off-by: Lee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/20221112151835.39059-12-aidanmacdonald.0x0@gmail.com