drm/amd/display: Undo accidental fix revert in amdgpu_dm_ism.c

drm/amd/display: Undo accidental fix revert in amdgpu_dm_ism.c

[Why]

Pausing DPM power profiles during static screen caused a bunch of
audio/performance/clock issues that were addressed in this fix:
'commit 1412482b7143 ("Revert "drm/amd/display: pause the workload setting in dm"")'

This logic in function amdgpu_dm_crtc_vblank_control_worker() was moved
to amdgpu_dm_ism.c, but the fix was lost in the process.

[How]

Reapply the fix to amdgpu_dm_ism.c

Fixes: 754003486c3c ("drm/amd/display: Add Idle state manager(ISM)")
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>
Signed-off-by: Leo Li <sunpeng.li@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>