drm/amd/display: default force_single_disp_pipe_split = 1 on RV

1080p idle, stutter efficiency goes up from 95.8% to 97.8%
result in 5mW saving from APU and 8mW saving from DDR4

Signed-off-by: Tony Cheng <tony.cheng@amd.com>
Reviewed-by: Yongqiang Sun <yongqiang.sun@amd.com>
Acked-by: Harry Wentland <Harry.Wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/dcn10/dcn10_resource.c

@@ -430,6 +430,7 @@ static const struct dc_debug debug_defaults_drv = {
 		.disable_pplib_wm_range = false,
 		.pplib_wm_report_mode = WM_REPORT_DEFAULT,
 		.pipe_split_policy = MPC_SPLIT_AVOID_MULT_DISP,
+		.force_single_disp_pipe_split = true,
 		.disable_dcc = DCC_ENABLE,
 		.voltage_align_fclk = true,
 		.disable_stereo_support = true,