The pointer to a platform_device struct must not be dereferenced after
the device has been unregistered.

This bug produces a crash when unloading the ci13xxx kernel module
compiled with CONFIG_PAGE_POISONING enabled.
Signed-off-by: NLothar Waßmann <LW@KARO-electronics.de>
Cc: stable <stable@vger.kernel.org> # 3.6
Acked-by: NAlexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>