linux-phytec-fsl

PCI: Skip id checking if no id is passed

Will get warning when pci stub driver is built-in kenel like:
pci-stub: invalid id string ""

So stop early if no id is passed.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>