net/i40e: add support for representor ports

net/i40e: add support for representor ports

Add support for virtual function representor ports to the i40e PF
driver. When SR-IOV virtual functions devices are enabled a
corresponding representor port for each VF can be enabled, in the
process in which the i40e PMD is running, by specifying the
representor devargs with the list of VF ports that representors
are to be created for.

An example of the devargs which would create VF representor for virtual
functions 0,2,4,5,6 and 7 is:

-w DBDF,representor=[0,2,4-7]

and to just specify a single representor on virtual function 3 (switch
port id):

-w DBDF,representor=3

Signed-off-by: Declan Doherty <declan.doherty@intel.com>
Signed-off-by: Mohammad Abdul Awal <mohammad.abdul.awal@intel.com>
Signed-off-by: Remy Horton <remy.horton@intel.com>
Reviewed-by: Ferruh Yigit <ferruh.yigit@intel.com>