gpio: mt7621: Kill parent_device usage

This gpio controller sets the parent_device field, but doesn't have
any runtime PM functionality. Get rid of it.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Acked-by: Bartosz Golaszewski <brgl@bgdev.pl>
Link: https://lore.kernel.org/r/20220201120310.878267-7-maz@kernel.org

drivers/gpio/gpio-mt7621.c

@@ -239,7 +239,6 @@ mediatek_gpio_bank_probe(struct device *dev, int bank)
 
 	rg->chip.offset = bank * MTK_BANK_WIDTH;
 	rg->irq_chip.name = dev_name(dev);
-	rg->irq_chip.parent_device = dev;
 	rg->irq_chip.irq_unmask = mediatek_gpio_irq_unmask;
 	rg->irq_chip.irq_mask = mediatek_gpio_irq_mask;
 	rg->irq_chip.irq_mask_ack = mediatek_gpio_irq_mask;