The PFVF protocol "enable" functions are direction specific but not
device specific. Move the protocol enable function for the PF into the
PF specific protocol file for better file organization and duplicated
code reduction.

NOTE: the patch keeps gen4 disabled as it doesn't have full PFVF
support yet.
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>