of/irq: do irq resolution in platform_get_irq_byname()

The commit 9ec36cafe4
"of/irq: do irq resolution in platform_get_irq" from Rob Herring -
moves resolving of the interrupt resources in platform_get_irq().
But this solution isn't complete because platform_get_irq_byname()
need to be modified the same way.

Hence, fix it by adding interrupt resolution code at the
platform_get_irq_byname() function too.

Cc: Russell King <linux@arm.linux.org.uk>
Cc: Rob Herring <robh@kernel.org>
Cc: Tony Lindgren <tony@atomide.com>
Cc: Grant Likely <grant.likely@linaro.org>
Cc: Thierry Reding <thierry.reding@gmail.com>

Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Grant Likely <grant.likely@linaro.org>

drivers/of/irq.c

@@ -405,6 +405,28 @@ int of_irq_get(struct device_node *dev, int index)
 	return irq_create_of_mapping(&oirq);
 }
 
+/**
+ * of_irq_get_byname - Decode a node's IRQ and return it as a Linux irq number
+ * @dev: pointer to device tree node
+ * @name: irq name
+ *
+ * Returns Linux irq number on success, or -EPROBE_DEFER if the irq domain
+ * is not yet created, or error code in case of any other failure.
+ */
+int of_irq_get_byname(struct device_node *dev, const char *name)
+{
+	int index;
+
+	if (unlikely(!name))
+		return -EINVAL;
+
+	index = of_property_match_string(dev, "interrupt-names", name);
+	if (index < 0)
+		return index;
+
+	return of_irq_get(dev, index);
+}
+
 /**
  * of_irq_count - Count the number of IRQs a node uses
  * @dev: pointer to device tree node