ARM: mach-shmobile: Allow GPIO chips to register IRQ mappings.

As non-PFC chips are added that may support IRQs, pass through to the
generic helper. This follows the the SH change.
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>

arch/arm/mach-shmobile/include/mach/gpio.h

@@ -35,12 +35,12 @@ static inline int gpio_cansleep(unsigned gpio)
 
 static inline int gpio_to_irq(unsigned gpio)
 {
-	return -ENOSYS;
+	return __gpio_to_irq(gpio);
 }
 
 static inline int irq_to_gpio(unsigned int irq)
 {
-	return -EINVAL;
+	return -ENOSYS;
 }
 
 #endif /* CONFIG_GPIOLIB */