mtd: nand: sunxi: fix sunxi_nand_chips_cleanup()

commit 8e375ccd 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: 1fef62c1 ("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: Kamal Mostafa <kamal@canonical.com>

drivers/mtd/nand/sunxi_nand.c

@@ -1306,6 +1306,7 @@ static void sunxi_nand_chips_cleanup(struct sunxi_nfc *nfc)
 					node);
 		nand_release(&chip->mtd);
 		sunxi_nand_ecc_cleanup(&chip->nand.ecc);
+		list_del(&chip->node);
 	}
 }