irq_domain/powerpc: Replace custom xlate functions with library functions

This patch converts a number of the powerpc drivers to use the common library
of irq_domain xlate functions, dropping a bunch of lines in the process.

v5: - Remove tsi108 changes from patch

Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Cc: Rob Herring <rob.herring@calxeda.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Milton Miller <miltonm@bga.com>
Tested-by: Olof Johansson <olof@lixom.net>
diff --git a/drivers/gpio/gpio-mpc8xxx.c b/drivers/gpio/gpio-mpc8xxx.c
index 149d987..e6568c1 100644
--- a/drivers/gpio/gpio-mpc8xxx.c
+++ b/drivers/gpio/gpio-mpc8xxx.c
@@ -296,24 +296,9 @@
 	return 0;
 }
 
-static int mpc8xxx_gpio_irq_xlate(struct irq_domain *h, struct device_node *ct,
-				  const u32 *intspec, unsigned int intsize,
-				  irq_hw_number_t *out_hwirq,
-				  unsigned int *out_flags)
-
-{
-	/* interrupt sense values coming from the device tree equal either
-	 * EDGE_FALLING or EDGE_BOTH
-	 */
-	*out_hwirq = intspec[0];
-	*out_flags = intspec[1];
-
-	return 0;
-}
-
 static struct irq_domain_ops mpc8xxx_gpio_irq_ops = {
 	.map	= mpc8xxx_gpio_irq_map,
-	.xlate	= mpc8xxx_gpio_irq_xlate,
+	.xlate	= irq_domain_xlate_twocell,
 };
 
 static struct of_device_id mpc8xxx_gpio_ids[] __initdata = {