mtd: nand: sunxi: fix sunxi_nand_chips_cleanup()

mtd: nand: sunxi: fix sunxi_nand_chips_cleanup()

commit 8e375ccda31ccc73b087134e263c48d2114534f4 upstream.

The sunxi_nand_chips_cleanup() function is missing a call to list_del()
which generates a double free error.

Reported-by: Priit Laes <plaes@plaes.org>
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Fixes: 1fef62c1423b ("mtd: nand: add sunxi NAND flash controller support")
Tested-by: Priit Laes <plaes@plaes.org>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>