mtd: rawnand: atmel: fix refcount issue in atmel_nand_controller_init

In the Linux kernel, the following vulnerability has been resolved: mtd: rawnand: atmel: fix refcount issue in atmel_nand_controller_init The reference counting issue happens in several error handling paths on a refcounted object "nc->dmac". In these paths, the function simply returns the error code, forgetting to balance the reference count of "nc->dmac", increased earlier by dma_request_channel(), which may cause refcount leaks. Fix it by decrementing the refcount of specific object in those error paths.