crypto: qat - set PFVF_MSGORIGIN just before sending

In this implementation of the PFVF protocol every egressing message must
include the ADF_PFVF_MSGORIGIN_SYSTEM flag. However, this flag can be set
on all the outbound messages just before sending them rather than at
message build time, as currently done.

Remove the unnecessary code duplication by setting the
ADF_PFVF_MSGORIGIN_SYSTEM flag only once at send time in
adf_gen2_pfvf_send().

Signed-off-by: Marco Chiappero <marco.chiappero@intel.com>
Reviewed-by: Giovanni Cabiddu <giovanni.cabiddu@intel.com>
Reviewed-by: Fiona Trahe <fiona.trahe@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>