mfd/db8500-prcmu: use the irq_domain_add_simple()

To be able to use SPARSE_IRQ while yet not using device tree,
we need to use irq_domain_add_simple() that will allocate
descriptors for the IRQs in the non-DT case, and fall back
to using the linear irqdomain in the DT case.

Cc: Lee Jones <lee.jones@linaro.org>
Cc: Samuel Ortiz <sameo@linux.intel.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/mfd/db8500-prcmu.c

@@ -2697,9 +2697,15 @@ static struct irq_domain_ops db8500_irq_ops = {
 
 static int db8500_irq_init(struct device_node *np)
 {
-	db8500_irq_domain = irq_domain_add_legacy(
-		np, NUM_PRCMU_WAKEUPS, IRQ_PRCMU_BASE,
-		0, &db8500_irq_ops, NULL);
+	int irq_base = -1;
+
+	/* In the device tree case, just take some IRQs */
+	if (!np)
+		irq_base = IRQ_PRCMU_BASE;
+
+	db8500_irq_domain = irq_domain_add_simple(
+		np, NUM_PRCMU_WAKEUPS, irq_base,
+		&db8500_irq_ops, NULL);
 
 	if (!db8500_irq_domain) {
 		pr_err("Failed to create irqdomain\n");