drm/amd/display: Program triplebuffer on all pipes

[WHY]
Triplebuffer should be programmed on all pipes.
Some code assumed it only needed to be called on top
pipe, but as the HWSS function does not account
for that, it must be called on every pipe.

[HOW]
Remove condition to not program triplebuffer
on non-top/next pipe. Call the function
unconditionally on all pipes.

Reviewed-by: Dillon Varone <dillon.varone@amd.com>
Reviewed-by: Aric Cyr <aric.cyr@amd.com>
Signed-off-by: Sung Lee <Sung.Lee@amd.com>
Signed-off-by: Ray Wu <ray.wu@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>