net/nfp: allocate ethernet device from PF probe function

net/nfp: allocate ethernet device from PF probe function

NFP can support several physical ports per PF device. Depending on
firmware info, one or more eth_dev objects will need to be created.

This patch adds the call to create just one eth_dev by now with future
commits supporting the multiport option. Once the eth_dev has been
created, probe function invokes pmd initialization with the new eth_dev.

Signed-off-by: Alejandro Lucero <alejandro.lucero@netronome.com>