devargs: restore device type API

devargs: restore device type API

Revert "devargs: make device types generic"

This commit broke the rte_devargs API by changing the meaning of
the rte_devtype enum.

Restore the previous API, unit tests and function calls.
Introduce parallel enum that acts as translation between previous API
and current structures.

Restoring the previous API means that -w and -b are not usable anymore
with any bus having implemented the "parse" operation. Only PCI devices
can be used with -w and -b, virtual devices are declared using vdev.

This (partially) reverts commit bd279a79366f50a4893fb84db91bbf64b56f9fb1.

Signed-off-by: Gaetan Rivet <gaetan.rivet@6wind.com>