Revert "drm/amdgpu/display: change pipe policy for DCN 2.1"

This reverts commit fa458eb1.

The issue is no longer present even with this commit present
as verified by the original reporter.

Reviewed-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Link: https://gitlab.freedesktop.org/drm/amd/-/issues/1849#note_1759599


Signed-off-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>