drm/amd/display: Pass pwrseq inst for backlight and ABM

[Why]
OTG inst and pwrseq inst mapping is not align therefore we cannot use
otg_inst as pwrseq inst to get DCIO register.

[How]
1. Pass the correct pwrseq instance to dmub when set abm pipe.
2. LVTMA control index change from panel_inst to pwrseq_inst.

Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Reviewed-by: Phil Hsieh <phil.hsieh@amd.com>
Acked-by: Rodrigo Siqueira <rodrigo.siqueira@amd.com>
Signed-off-by: Lewis Huang <lewis.huang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>