Currently PFVF messages are created upfront in the CSR format, that is
PF2VF messages starting from bit 0 and VF2PF from bit 16, and passed
along unmodified to the PFVF send function.

Refactor the code to allow the VF2PF messages to be built starting from
bit 0, as for the PF2VF messages. Shift the VF to PF messages just
before sending them, and refactor the send logic to handle messages
properly depending on the direction.

As a result all the messages are composed the same way regardless of
the direction.
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>