dm: pci: Tidy up auto-config error handling

When the auto-configuration process fails for a device (generally due to
lack of memory) we should return the error correctly so that we don't
continue to try memory allocations which will fail.

Adjust the code to check for errors and abort if something goes wrong.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>