drm/amd/display: Don't map ATOM_ENABLE to ATOM_INIT

[Why]
In DCN hardware sequencer we do actually call ATOM_INIT correctly per
pipe. The workaround is not necessary for command table offloading.

[How]
Drop the workaround since it's not needed.

Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Reviewed-by: Chris Park <Chris.Park@amd.com>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>