gpio: pca953x: prevent freeing IRQ 0 on probe error

[H Hartley Sweeten <hartleys@visionengravers.com>]

If CONFIG_GPIO_PCA953X_IRQ is enabled and an error occurs in the probe
before pca953x_irq_setup() is called chip->client->irq will be 0 due to
the kmalloc.  pca953x_irq_teardown() will then try to free_irq(0, chip)
which will produce a:

	WARN(1, "Trying to free already-free IRQ %d\n", irq);

Add an error path to prevent this.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Grant Likely <grant.likely@secretlab.ca>

---

diff --git a/drivers/gpio/pca953x.c b/drivers/gpio/pca953x.c
index 2fc25de..e1ff4d5 100644
--- a/drivers/gpio/pca953x.c
+++ b/drivers/gpio/pca953x.c
@@ -523,7 +523,7 @@ static int __devinit pca953x_probe(struct i2c_client *client,
 	if (pdata == NULL) {
 		dev_dbg(&client->dev, "no platform data\n");
 		ret = -EINVAL;
-		goto out_failed;
+		goto out_free;
 	}
 
 	chip->client = client;
@@ -541,20 +541,20 @@ static int __devinit pca953x_probe(struct i2c_client *client,
 
 	ret = pca953x_read_reg(chip, PCA953X_OUTPUT, &chip->reg_output);
 	if (ret)
-		goto out_failed;
+		goto out_free;
 
 	ret = pca953x_read_reg(chip, PCA953X_DIRECTION, &chip->reg_direction);
 	if (ret)
-		goto out_failed;
+		goto out_free;
 
 	/* set platform specific polarity inversion */
 	ret = pca953x_write_reg(chip, PCA953X_INVERT, pdata->invert);
 	if (ret)
-		goto out_failed;
+		goto out_free;
 
 	ret = pca953x_irq_setup(chip, id);
 	if (ret)
-		goto out_failed;
+		goto out_free;
 
 	ret = gpiochip_add(&chip->gpio_chip);
 	if (ret)
@@ -572,6 +572,7 @@ static int __devinit pca953x_probe(struct i2c_client *client,
 
 out_failed:
 	pca953x_irq_teardown(chip);
+out_free:
 	kfree(chip->dyn_pdata);
 	kfree(chip);
 	return ret;