i2c: Remove unneeded xxx_set_drvdata(..., NULL) calls

There is simply no reason to be manually setting the private driver
data to NULL in the remove/fail to probe cases.  This is just extra
cruft code that can be removed.

A few notes:
* Nothing relies on drvdata being set to NULL.
* The __device_release_driver() function eventually calls
  dev_set_drvdata(dev, NULL) anyway, so there's no need to do it
  twice.
* I verified that there were no cases where xxx_get_drvdata() was
  being called in these drivers and checking for / relying on the NULL
  return value.

This could be cleaned up kernel-wide but for now just take the baby
step and remove from the i2c subsystem.

Reported-by: Wolfram Sang <wsa@the-dreams.de>
Reported-by: Stephen Warren <swarren@wwwdotorg.org>
Signed-off-by: Doug Anderson <dianders@chromium.org>
Reviewed-by: Jean Delvare <khali@linux-fr.org>
Acked-by: Peter Korsgaard <jacmet@sunsite.dk>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Marek Vasut <marex@denx.de>
Signed-off-by: Wolfram Sang <wolfram@the-dreams.de>

drivers/i2c/busses/i2c-octeon.c

@@ -595,7 +595,7 @@ static int octeon_i2c_probe(struct platform_device *pdev)
 	result = i2c_add_adapter(&i2c->adap);
 	if (result < 0) {
 		dev_err(i2c->dev, "failed to add adapter\n");
-		goto fail_add;
+		goto out;
 	}
 	dev_info(i2c->dev, "version %s\n", DRV_VERSION);
 
@@ -603,8 +603,6 @@ static int octeon_i2c_probe(struct platform_device *pdev)
 
 	return 0;
 
-fail_add:
-	platform_set_drvdata(pdev, NULL);
 out:
 	return result;
 };
@@ -614,7 +612,6 @@ static int octeon_i2c_remove(struct platform_device *pdev)
 	struct octeon_i2c *i2c = platform_get_drvdata(pdev);
 
 	i2c_del_adapter(&i2c->adap);
-	platform_set_drvdata(pdev, NULL);
 	return 0;
 };