drm/amd/display: Fix fclk idle state

[Why]
The earlier change 'Fix 6x4K displays' led to fclk value
idling at higher DPM level.

[How]
Apply the fix only to respective multi-display configuration.
Signed-off-by: Roman Li <Roman.Li@amd.com>
Reviewed-by: Feifei Xu <Feifei.Xu@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/dce/dce_clk_mgr.c

@@ -591,7 +591,15 @@ static void dce11_pplib_apply_display_requirements(
 			dc,
 			context->bw.dce.sclk_khz);
 
-	pp_display_cfg->min_dcfclock_khz = pp_display_cfg->min_engine_clock_khz;
+	/*
+	 * As workaround for >4x4K lightup set dcfclock to min_engine_clock value.
+	 * This is not required for less than 5 displays,
+	 * thus don't request decfclk in dc to avoid impact
+	 * on power saving.
+	 *
+	 */
+	pp_display_cfg->min_dcfclock_khz = (context->stream_count > 4)?
+			pp_display_cfg->min_engine_clock_khz : 0;
 
 	pp_display_cfg->min_engine_clock_deep_sleep_khz
 			= context->bw.dce.sclk_deep_sleep_khz;