powerpc/pmac: Fix dangling pointers

Fix I2C-drivers which missed setting clientdata to NULL before freeing the
structure it points to. Also fix drivers which do this _after_ the structure
was freed already.
Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
Cc: Colin Leroy <colin@colino.net>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

drivers/macintosh/therm_adt746x.c

@@ -182,6 +182,7 @@ remove_thermostat(struct i2c_client *client)
 
 	thermostat = NULL;
 
+	i2c_set_clientdata(client, NULL);
 	kfree(th);
 
 	return 0;
@@ -399,6 +400,7 @@ static int probe_thermostat(struct i2c_client *client,
 	rc = read_reg(th, CONFIG_REG);
 	if (rc < 0) {
 		dev_err(&client->dev, "Thermostat failed to read config!\n");
+		i2c_set_clientdata(client, NULL);
 		kfree(th);
 		return -ENODEV;
 	}