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

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 <[email protected]>
Reported-by: Stephen Warren <[email protected]>
Signed-off-by: Doug Anderson <[email protected]>
Reviewed-by: Jean Delvare <[email protected]>
Acked-by: Peter Korsgaard <[email protected]>
Reviewed-by: Mika Westerberg <[email protected]>
Reviewed-by: Marek Vasut <[email protected]>
Signed-off-by: Wolfram Sang <[email protected]>