Low four bits are downstream port count. High bit indicates peer OUI
support. OUI matching will allow us to do additional per-sink handling
for things like DP->VGA bandwidth limits or (hopefully) the iMac-as-
display hack.
Signed-off-by: Adam Jackson <ajax@redhat.com> Reviewed-by: Jerome Glisse <jglisse@redhat.com> Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch> Acked-by: Alex Deucher <alexander.deucher@amd.com> Signed-off-by: Dave Airlie <airlied@redhat.com>