gma500: clean up error handling in init

The main problem with this error handling was that it didn't clean up if
i2c_add_numbered_adapter() failed.  This code is pretty old, and doesn't
match with today's checkpatch.pl standards so I took the opportunity to
tidy it up a bit.  I changed the NULL comparison, and removed the
WARNING message if kzalloc() fails and updated the label names.

Fixes: 1b082ccf ("gma500: Add Oaktrail support")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Patrik Jakobsson <patrik.r.jakobsson@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/X8ikkAqZfnDO2lu6@mwanda

drivers/gpu/drm/gma500/oaktrail_hdmi_i2c.c

@@ -279,11 +279,8 @@ int oaktrail_hdmi_i2c_init(struct pci_dev *dev)
 	hdmi_dev = pci_get_drvdata(dev);
 
 	i2c_dev = kzalloc(sizeof(struct hdmi_i2c_dev), GFP_KERNEL);
-	if (i2c_dev == NULL) {
-		DRM_ERROR("Can't allocate interface\n");
-		ret = -ENOMEM;
-		goto exit;
-	}
+	if (!i2c_dev)
+		return -ENOMEM;
 
 	i2c_dev->adap = &oaktrail_hdmi_i2c_adapter;
 	i2c_dev->status = I2C_STAT_INIT;
@@ -300,16 +297,23 @@ int oaktrail_hdmi_i2c_init(struct pci_dev *dev)
 			  oaktrail_hdmi_i2c_adapter.name, hdmi_dev);
 	if (ret) {
 		DRM_ERROR("Failed to request IRQ for I2C controller\n");
-		goto err;
+		goto free_dev;
 	}
 
 	/* Adapter registration */
 	ret = i2c_add_numbered_adapter(&oaktrail_hdmi_i2c_adapter);
-	return ret;
+	if (ret) {
+		DRM_ERROR("Failed to add I2C adapter\n");
+		goto free_irq;
+	}
 
-err:
+	return 0;
+
+free_irq:
+	free_irq(dev->irq, hdmi_dev);
+free_dev:
 	kfree(i2c_dev);
-exit:
+
 	return ret;
 }