Fix segfault on probing a non-PCI platform device on a system with PCI.

Emma Anholt requested to merge anholt/xserver:platform-crash into master

Some Broadcom set-top-box boards have PCI busses, but the GPU is still probed through DT. We would dereference a null busid here in that case.

Signed-off-by: Eric Anholt

Merge request reports