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>