BugLink: https://bugs.launchpad.net/bugs/1878232

commit 320092a0 upstream.

Unregister the NAND device from the NAND subsystem when removing a denali
NAND controller, otherwise the MTD attached to the NAND device is still
exposed by the MTD layer, and accesses to this device will likely crash
the system.

Fixes: 2a0a288e ("mtd: denali: split the generic driver and PCI layer")
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Acked-by: Dinh Nguyen <dinguyen@opensource.altera.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ian May <ian.may@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>