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

@@ -517,8 +517,10 @@ static int pca953x_irq_setup(struct pca953x_chip *chip,
 
 static void pca953x_irq_teardown(struct pca953x_chip *chip)
 {
-	if (chip->irq_base != -1)
+	if (chip->irq_base != -1) {
+		irq_free_descs(chip->irq_base, chip->gpio_chip.ngpio);
 		free_irq(chip->client->irq, chip);
+	}
 }
 #else /* CONFIG_GPIO_PCA953X_IRQ */
 static int pca953x_irq_setup(struct pca953x_chip *chip,