usb hubs tend to expose removable attribute as unknown. This makes some
problems like a hub for external usb ports in pogo pins is unknown and
also soldered hubs in laptops for keyboard+touchpad.
Let's set internal when the device removable attribute is fixed and
external when removable, but when it's unknown lets check the parent
ports (not the host devpath!=0) attribute to decide.
This makes us to missdetect pogo ping connected external usb hubs but
let us to correctly detect laptop internal keyboards and touchpads that
are wired through hubs instead directly.
This behaviour is more desirable, as actually there are a bunch of
laptops with this setup.
Fixes: a4381cae8b.
David Santamaría Rogado