Allocate local call data with proper alignment
The kernel must provide both pack data and extra data to the module with the guarantee that it is properly aligned. The SivDK must access the values by directly copying the respectful types, without any need to do memcpy. However, the kernel may not assert that the data provided by the module is properly aligned (for network data, misalignment is the normal behavior), and must perform proper memcpy when accessing this data. This will simplify SivDK code and simplify the way of using low-level functions directly.