drm/amd/display: disable PSR/ABM before destroy DMCU struct

[Why]
1. DMCU is not running on some platform but driver still send ABM
   command. It may cause assert due to DMCU is not alive.
2. To make sure PSR disable when driver disable

[How]
1. Add dmcu_is_running in ABM struct, driver can check this flag to
   determine driver should send ABM command or not.
2. Send PSR disable command when destroy PSR

Signed-off-by: Paul Hsieh <paul.hsieh@amd.com>
Reviewed-by: Anthony Koo <Anthony.Koo@amd.com>
Acked-by: Leo Li <sunpeng.li@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>