gpio/pca953x: Fix IRQ support.

It seems that in the normal case, IRQ_NOREQUEST needs to be explicitly
cleared, otherwise claiming the interrupt fails.
In the case of sparse interrupts, the descriptor needs to be allocated
first.
Signed-off-by: David Jander <david@protonic.nl>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

drivers/gpio/gpio-pca953x.c

@@ -474,12 +474,16 @@ static int pca953x_irq_setup(struct pca953x_chip *chip,
 		 * this purpose.
 		 */
 		chip->irq_stat &= chip->reg_direction;
-		chip->irq_base = pdata->irq_base;
 		mutex_init(&chip->irq_lock);
 
+		chip->irq_base = irq_alloc_descs(-1, pdata->irq_base, chip->gpio_chip.ngpio, -1);
+		if (chip->irq_base < 0)
+			goto out_failed;
+
 		for (lvl = 0; lvl < chip->gpio_chip.ngpio; lvl++) {
 			int irq = lvl + chip->irq_base;
 
+			irq_clear_status_flags(irq, IRQ_NOREQUEST);
 			irq_set_chip_data(irq, chip);
 			irq_set_chip_and_handler(irq, &pca953x_irq_chip,
 						 handle_simple_irq);