Input: mtk-pmic-keys - use get_irq_byname() instead of index

Some pmics of the mt6397 family (such as MT6358), have two IRQs per
physical key: one for press event, another for release event.

The mtk-pmic-keys driver assumes that each key only has one
IRQ. The key index and the RES_IRQ resource index have a 1/1 mapping.

This won't work for MT6358, as we have multiple resources (2) for one key.

To prepare mtk-pmic-keys to support MT6358, retrieve IRQs by name
instead of by index.

Signed-off-by: Mattijs Korpershoek <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Dmitry Torokhov <[e-mail]>

drivers/input/keyboard/mtk-pmic-keys.c

···
 	unsigned int keycount;
 	struct mt6397_chip *pmic_chip = dev_get_drvdata(pdev->dev.parent);
 	struct device_node *node = pdev->dev.of_node, *child;
+	static const char *const irqnames[] = { "powerkey", "homekey" };
 	struct mtk_pmic_keys *keys;
 	const struct mtk_pmic_regs *mtk_pmic_regs;
 	struct input_dev *input_dev;
···
 	input_dev->id.version = 0x0001;
 
 	keycount = of_get_available_child_count(node);
-	if (keycount > MTK_PMIC_MAX_KEY_COUNT) {
+	if (keycount > MTK_PMIC_MAX_KEY_COUNT ||
+	    keycount > ARRAY_SIZE(irqnames)) {
 		dev_err(keys->dev, "too many keys defined (%d)\n", keycount);
 		return -EINVAL;
 	}
···
 	for_each_child_of_node(node, child) {
 		keys->keys[index].regs = &mtk_pmic_regs->keys_regs[index];
 
-		keys->keys[index].irq = platform_get_irq(pdev, index);
+		keys->keys[index].irq =
+			platform_get_irq_byname(pdev, irqnames[index]);
 		if (keys->keys[index].irq < 0) {
 			of_node_put(child);
 			return keys->keys[index].irq;