drm/amd/display: Catch failures for amdgpu_dm_commit_zero_streams()

amdgpu_dm_commit_zero_streams() returns a DC error code that isn't
checked. Add an explicit check to this and fail dm_suspend() if it
is not DC_OK.

Reviewed-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Wayne Lin <wayne.lin@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>