[stable] i2c: dev: Fix the race between the release of i2c_dev and cdev

Please pick this fix for all stable branches:

commit 1413ef638abae4ab5621901cf4d8ef08a4a48ba6 Author: Kevin Hao haokexin@gmail.com Date: Fri Oct 11 23:00:14 2019 +0800

i2c: dev: Fix the race between the release of i2c_dev and cdev

I don't know whether it will apply cleanly to all of them; I can deal with those where it doesn't.

Ben.