bus: introduce parsing functionality

This operation can be used either to validate that a device
representation can be understood by a bus, as well as store the resulting
specialized device representation in any format determined by the bus.

Implementing this function allows EAL initialization routines to infer
which bus should handle a device. This is used as a way to respect
backward compatibility.

This API will disappear once this compatibility is not enforced anymore.

Signed-off-by: Gaetan Rivet <gaetan.rivet@6wind.com>
Acked-by: Bruce Richardson <bruce.richardson@intel.com>
Acked-by: Shreyansh Jain <shreyansh.jain@nxp.com>