drm/dp/mst: add some defines for logical/physical ports

[ Upstream commit ccf03d6995fa4b784f5b987726ba98f4859bf326 ]

This just removes the magic number.

Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
2 files changed