comedi: dt9812: fix DMA buffers on stack

comedi: dt9812: fix DMA buffers on stack

This is an automated ID intended to aid in discovery of potential security vulnerabilities. The actual impact and attack plausibility have not yet been proven.
This ID is fixed in Linux Kernel version v5.15.2 by commit 20cebb8b620dc987e55ddc46801de986e081757e, it was introduced in version v2.6.29 by commit 63274cd7d38a3322d90b66a5bc976de1fb899051. For more details please see the references link.