drm/amd/display: add power_state and pme_pending flag

[what]
Adding power_state to dc.h and pme_pending flag to clk_mgr_internal.h

Reviewed-by: Charlene Liu <charlene.liu@amd.com>
Acked-by: Roman Li <roman.li@amd.com>
Signed-off-by: Muhammad Ahmed <ahmed.ahmed@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>