drm/amd/display: Fixed Intermittent blue screen on OLED panel

[why]
Changing to smaller modes on OLED panel caused a blue screen crash
as driver reported dram change during vactive when it shouldn't

[how]
Added an extra condition to prevent incorrect dram change timing
Signed-off-by: Naveed Ashfaq <Naveed.Ashfaq@amd.com>
Acked-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/dml/dcn20/display_mode_vba_20v2.c

@@ -2635,16 +2635,15 @@ static void dml20v2_DISPCLKDPPCLKDCFCLKDeepSleepPrefetchParametersWatermarksAndP
 	}
 
 	if (mode_lib->vba.DRAMClockChangeSupportsVActive &&
-			mode_lib->vba.MinActiveDRAMClockChangeMargin > 60) {
+			mode_lib->vba.MinActiveDRAMClockChangeMargin > 60 &&
+			mode_lib->vba.PrefetchMode[mode_lib->vba.VoltageLevel][mode_lib->vba.maxMpcComb] == 0) {
 		mode_lib->vba.DRAMClockChangeWatermark += 25;
 
 		for (k = 0; k < mode_lib->vba.NumberOfActivePlanes; ++k) {
-			if (mode_lib->vba.PrefetchMode[mode_lib->vba.VoltageLevel][mode_lib->vba.maxMpcComb] == 0) {
 			if (mode_lib->vba.DRAMClockChangeWatermark >
 			dml_max(mode_lib->vba.StutterEnterPlusExitWatermark, mode_lib->vba.UrgentWatermark))
 				mode_lib->vba.MinTTUVBlank[k] += 25;
 		}
-		}
 
 		mode_lib->vba.DRAMClockChangeSupport[0][0] = dm_dram_clock_change_vactive;
 	} else if (mode_lib->vba.DummyPStateCheck &&