Make the PFVF send function device specific.

This is in preparation for the introduction of PFVF support in the
qat_4xxx driver since the send logic differs between QAT GEN2 and
QAT GEN4 devices.
Signed-off-by: Marco Chiappero <marco.chiappero@intel.com>
Co-developed-by: Giovanni Cabiddu <giovanni.cabiddu@intel.com>
Signed-off-by: Giovanni Cabiddu <giovanni.cabiddu@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>