pci: fix device registration on FreeBSD

pci: fix device registration on FreeBSD

The FreeBSD implementation wasn't registering new devices
with the device framework on start up. However, common
code attempts to unregister them on shutdown which causes
a SEGFAULT. This fix makes the FreeBSD code do the same
thing as the Linux code for registration.

Fixes: 13a1317d3ba7 ("pci: create device list and fallback on its members")
Cc: stable@dpdk.org
Signed-off-by: Ben Walker <benjamin.walker@intel.com>
Acked-by: Shreyansh Jain <shreyansh.jain@nxp.com>