usb: Use hub port data to determine whether a port is removable

Hubs have a flag to indicate whether a given port carries removable devices
or not. This is not strictly accurate in that some built-in devices
will be flagged as removable, but followup patches will make use of platform
data to make this more reliable.

Signed-off-by: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>