thunderbolt: Re-calculate estimated bandwidth when allocation mode is enabled

When we program the initial bandwidth estimation the DPTX (graphics
driver) has not yet read the capabilities of the monitor so the values
used are the highest possible of the involved DisplayPort IN and OUT
adapters, not the actual monitor capabilities. To allow the graphics
more accurate bandwidth estimation re-calculate it once we receive the
bandwidth allocation mode enabled notification.

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