[Intel-gfx] [intel-gfx][PATCH] Displayport compliance tests 4.2.2.7 and 4.2.2.8

[Todd Previte]

Improve Displayport compliance support. These patches add support for    
the following tests in the Displayport Link CTS Core 1.2 rev1.1:

4.2.2.7: Branch Device Detection upon HPD Plug Event
4.2.2.8: EDID read on IRQ_HPD event after Branch Device detection

The patches require the initial Displayport compliance patch set in
order to operate correctly.