Reorganize the structure of the PFVF code by moving the content of
adf_pf2vf_msg.c and adf_vf2pf_msg.c.

The logic that handles high level messages has been moved to
adf_pfvf_pf_msg.c and adf_pfvf_vf_msg.c.
The implementation of low level communication primitives and the
protocol is now included in adf_pfvf_pf_proto.c and adf_pfvf_vf_proto.c.

In addition, the file adf_pf2vf_msg.h has been renamed in adf_pfvf_msg.h
since it common to PF and VF and the copyright date for the touched
files has been updated.
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>