CVE-2025-68238

In the Linux kernel, the following vulnerability has been resolved:

mtd: rawnand: cadence: fix DMA device NULL pointer dereference

The DMA device pointer `dma_dev` was being dereferenced before ensuring
that `cdns_ctrl->dmac` is properly initialized.

Move the assignment of `dma_dev` after successfully acquiring the DMA
channel to ensure the pointer is valid before use.