virtio-snd: Fix dynamic memory allocation for PCM I/O frames

[Cuda-Chen]

Fix the PCM I/O transfer mechanism when allocating memory during frame enqueuing and freeing it upon dequeuing.

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Summary by cubic

Fixes PCM TX frame memory handling in virtio-snd by deep-copying enqueued payloads and freeing buffers on dequeue. Prevents audio artifacts and memory leaks during PCM I/O.

• Bug Fixes
  • Allocate node and its buffer with null checks; copy payload into owned memory.
  • Free node->addr and node when the frame is fully consumed.
  • Ensure the mutex unlocks on allocation failures via a single exit path.
  • Removes payload pointer reuse that caused repeating audio artifacts.

^{Written for commit d52d30c. Summary will update on new commits.}

[cubic-dev-ai]

No issues found across 1 file

[jserv]

Thank @Cuda-Chen for contributing!