ehci: workaround for pci quirk timeout on ExoPC

The BIOS handoff for the unused EHCI controller on the ExoPC tablet
hangs for 90 seconds on boot.  Detect that device, skip negotiation
and force the handoff.

Signed-off-by: Andy Ross <andy.ross@windriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>