CVE-2021-47195

In the Linux kernel, the following vulnerability has been resolved: spi:
fix use-after-free of the add_lock mutex Commit 6098475d4cb4 (“spi: Fix
deadlock when adding SPI controllers on SPI buses”) introduced a
per-controller mutex. But mutex_unlock() of said lock is called after the
controller is already freed: spi_unregister_controller(ctlr) ->
put_device(&ctlr->dev) -> spi_controller_release(dev) ->
mutex_unlock(&ctrl->add_lock) Move the put_device() after the
mutex_unlock().