Make rte_bus opaque for non internal users.
This will make extending this object possible without breaking the ABI.
Introduce a new driver header and move rte_bus definition and helpers.
Update drivers and library to use the internal header.
Some applications may have been dereferencing rte_bus objects, mark
this object's accessors as stable.
Signed-off-by: David Marchand <david.marchand@redhat.com>
Acked-by: Bruce Richardson <bruce.richardson@intel.com>