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

commit 9dc79965 upstream.

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=97857Reviewed-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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/gpu/drm/radeon/radeon_dp_auxch.c

@@ -105,7 +105,7 @@ radeon_dp_aux_transfer_native(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg
 
 	tmp &= AUX_HPD_SEL(0x7);
 	tmp |= AUX_HPD_SEL(chan->rec.hpd);
-	tmp |= AUX_EN | AUX_LS_READ_EN | AUX_HPD_DISCON(0x1);
+	tmp |= AUX_EN | AUX_LS_READ_EN;
 
 	WREG32(AUX_CONTROL + aux_offset[instance], tmp);