Revert "drm/amd/display: fix bandwidth validation failure on DCN 2.1"

This commit causes dmesg-warn on several IGT tests on DCN 3.1.6: *ERROR*
link_enc_cfg_validate: Invalid link encoder assignments - 0x1c

Affected IGT tests include:
- amdgpu/[amd_assr|amd_plane|amd_hotplug]
- kms_atomic
- kms_color
- kms_flip
- kms_properties
- kms_universal_plane

and some other tests

This reverts commit 3a0fa3bc.

Cc: Melissa Wen <mwen@igalia.com>
Cc: Hamza Mahfooz <hamza.mahfooz@amd.com>
Reviewed-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Ivan Lipski <ivlipski@amd.com>
Signed-off-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

@@ -10753,7 +10753,7 @@ static int amdgpu_dm_atomic_check(struct drm_device *dev,
 			DRM_DEBUG_DRIVER("drm_dp_mst_atomic_check() failed\n");
 			goto fail;
 		}
-		status = dc_validate_global_state(dc, dm_state->context, false);
+		status = dc_validate_global_state(dc, dm_state->context, true);
 		if (status != DC_OK) {
 			DRM_DEBUG_DRIVER("DC global validation failure: %s (%d)",
 				       dc_status_to_str(status), status);