The NVMe over Fabrics target was storing the PCI device pointer for each
direct-mode controller, but it only really needs the PCI address, which
is exposed via the get_nvmf_subsystems RPC.
Also update the same code path to use the new spdk_pci_device_get_addr()
function for brevity.
Change-Id: I0708b3331b7c279c1a86f0d7459b5deb40dd7c89
Signed-off-by: Daniel Verkamp <daniel.verkamp@intel.com>