During early phases of enumeration, it is possible for a device to be
enumerated before its parent. When this occurs, the device assigned as
the parent will actually be a grandparent. During later phases of
enumeration, the parent device will in fact exist but will not match
what has already been assigned to the device.

This commit adds code to check for and update the parent device when
this situation occurs.

Closes #206

Signed-off-by: Chris Dickens <christopher.a.dickens@gmail.com>