drm/amd/display: Allow system to enter stutter on init

[Why]
Workaround was missing in one HW disable path,
meaning when all pipes are power gated, stutter was
not working

[How]
Add workaround for init_hw path for stutter
workaround

Signed-off-by: Anthony Koo <Anthony.Koo@amd.com>
Reviewed-by: Aric Cyr <Aric.Cyr@amd.com>
Acked-by: Leo Li <sunpeng.li@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>