CVE-2024-43815 crypto: mxs-dcp - Ensure payload is zero when using key slot

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

crypto: mxs-dcp - Ensure payload is zero when using key slot

We could leak stack memory through the payload field when running
AES with a key from one of the hardware’s key slots. Fix this by
ensuring the payload field is set to 0 in such cases.

This does not affect the common use case when the key is supplied
from main memory via the descriptor payload.