Revert "drm/radeon: fix DP link training issue with second 4K monitor"

This reverts commit 1a738347.

It caused at least some Kaveri laptops to incorrectly report DisplayPort
connectors as connected.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=97857


Cc: stable@vger.kernel.org
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Michel Dänzer <michel.daenzer@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>