The PCI lib defines the types and methods allowing to use PCI elements.
The PCI bus implements a bus driver for PCI devices by constructing
rte_bus elements using the PCI lib.
Move the relevant code out of the EAL to its expected place.
Libraries, drivers, unit tests and applications are updated to use the
new rte_bus_pci.h header when necessary.
Signed-off-by: Gaetan Rivet <gaetan.rivet@6wind.com>