drm/amd/display: Change default Z8 watermark values

[Why & How]
Previous Z8 watermark values were causing flickering and OTC underflow.
Updating Z8 watermark values based on the measurement.

Reviewed-by: Nicholas Kazlauskas <Nicholas.Kazlauskas@amd.com>
Cc: Mario Limonciello <mario.limonciello@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
Acked-by: Alan Liu <HaoPing.Liu@amd.com>
Signed-off-by: Leo Chen <sancchen@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

Author: Leo Chen

drivers/gpu/drm/amd/display/dc/dml/dcn314/dcn314_fpu.c

@@ -149,8 +149,8 @@ static struct _vcs_dpi_soc_bounding_box_st dcn3_14_soc = {
 	.num_states = 5,
 	.sr_exit_time_us = 16.5,
 	.sr_enter_plus_exit_time_us = 18.5,
-	.sr_exit_z8_time_us = 210.0,
-	.sr_enter_plus_exit_z8_time_us = 310.0,
+	.sr_exit_z8_time_us = 268.0,
+	.sr_enter_plus_exit_z8_time_us = 393.0,
 	.writeback_latency_us = 12.0,
 	.dram_channel_width_bytes = 4,
 	.round_trip_ping_latency_dcfclk_cycles = 106,