drm/amd/display: modify init dc_power_state

drm/amd/display: modify init dc_power_state

[why]
initialize the power state for dc use,
but dc_set_power_state it not called at D3.
It would cause can't recognize last power state

[how]
remove initialize the power state for dc use, it is not necessary.

Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: Brandon Syu <Brandon.Syu@amd.com>
Signed-off-by: Roman Li <roman.li@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>