thunderbolt: Increase DPRX capabilities read timeout

Some graphics drivers such as i915 support runtime power management and
if there is nothing connected at the moment they will runtime suspend to
save power. At least i915 is polling for new connections every 10
seconds if the hardware does support sending PME. To allow i915 and
other graphics from detect the just established DisplayPort tunnel allow
the DPRX capabilities read to take up to 12 seconds.

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>