Queue-handling code in enqueue is made generic, so it can
be used by other services in future. This is done by
- Removing all sym-specific refs in input params - replace with void ptrs.
- Wrapping this generic enqueue with the sym-specific enqueue
called through the API.
- Setting a fn ptr for build_request in qp on qp creation
- Passing void * params to this, in the service-specific implementation
qat_sym_build_request cast back to sym structs.