drm/amd/display: Update DCN302 SR Exit Latency

[Why&How]
Update SR Exit Latency to fix screen flickering caused due to OTG
underflow. This is the recommended value given by the hardware IP team.
Signed-off-by: Joshua Aberback <joshua.aberback@amd.com>
Acked-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/dcn302/dcn302_resource.c

@@ -164,7 +164,7 @@ struct _vcs_dpi_soc_bounding_box_st dcn3_02_soc = {
 
 		.min_dcfclk = 500.0, /* TODO: set this to actual min DCFCLK */
 		.num_states = 1,
-		.sr_exit_time_us = 12,
+		.sr_exit_time_us = 15.5,
 		.sr_enter_plus_exit_time_us = 20,
 		.urgent_latency_us = 4.0,
 		.urgent_latency_pixel_data_only_us = 4.0,