pcie: Use mapper calls to lookup busnames

This is a reaction to a /org/openbmc/managers/System API update.
The update removes the bus name field from the 'GetObjectByxxx'
method responses.

Change-Id: I061f8071097b4e870031198a509abe48a4128d82
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
1 file changed