devargs: introduce new parsing helper

devargs: introduce new parsing helper

Introduce a more versatile helper to parse device strings. This
helper expects a generic rte_devargs structure as storage in order not
to require API changes in the future, should this structure be
updated.

The old equivalent function is thus being deprecated, as its API does
not allow to accompany rte_devargs evolutions.

A deprecation notice is issued.

This new helper will parse bus information as well as device name and
device parameters. It does not allocate an rte_devargs structure and
expects one to be given as input.

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