Originally reported at:
  https://bugzilla.gnome.org/show_bug.cgi?id=701956
Please refer to the original bug report if more details are needed.

When MM detects a device in the 'pci' subsystem, it should:
 * check whether the device is in a special new whitelist of devices to always
accept.
 * check whether the device uses a serial kernel driver, and if so, treat it as
if it was in the serial-adapters greylist (e.g. only probe during manual
Scan()).
 * otherwise, skip the device all together