gpio: tegra186: Set affinity callback to parent

This assigns the .irq_set_affinity to the parent callback.
I assume the Tegra186 is an SMP system so this would be
beneficial.

I used the pattern making the hirerarchy tolerant for missing
parent as in Marc's earlier patch.
Suggested-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Cc: Thierry Reding <treding@nvidia.com>
Cc: Vidya Sagar <vidyas@nvidia.com>
Link: https://lore.kernel.org/r/20201117213351.249668-2-linus.walleij@linaro.org

drivers/gpio/gpio-tegra186.c

@@ -444,6 +444,16 @@ static int tegra186_irq_set_wake(struct irq_data *data, unsigned int on)
 	return 0;
 }
 
+static int tegra186_irq_set_affinity(struct irq_data *data,
+				     const struct cpumask *dest,
+				     bool force)
+{
+	if (data->parent_data)
+		return irq_chip_set_affinity_parent(data, dest, force);
+
+	return -EINVAL;
+}
+
 static void tegra186_gpio_irq(struct irq_desc *desc)
 {
 	struct tegra_gpio *gpio = irq_desc_get_handler_data(desc);
@@ -690,6 +700,7 @@ static int tegra186_gpio_probe(struct platform_device *pdev)
 	gpio->intc.irq_unmask = tegra186_irq_unmask;
 	gpio->intc.irq_set_type = tegra186_irq_set_type;
 	gpio->intc.irq_set_wake = tegra186_irq_set_wake;
+	gpio->intc.irq_set_affinity = tegra186_irq_set_affinity;
 
 	irq = &gpio->gpio.irq;
 	irq->chip = &gpio->intc;