drm/amd/display: Revert dram_clock_change_latency for DCN2.1

[WHY & HOW]
Using values provided by DF for latency may cause hangs in
multi display configurations. Revert change to previous value.
Tested-by: NDaniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: NSung Lee <sung.lee@amd.com>
Reviewed-by: NHaonan Wang <Haonan.Wang2@amd.com>
Acked-by: NEryk Brol <eryk.brol@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/dcn21/dcn21_resource.c

@@ -296,7 +296,7 @@ struct _vcs_dpi_soc_bounding_box_st dcn2_1_soc = {
 	.num_banks = 8,
 	.num_chans = 4,
 	.vmm_page_size_bytes = 4096,
-	.dram_clock_change_latency_us = 11.72,
+	.dram_clock_change_latency_us = 23.84,
 	.return_bus_width_bytes = 64,
 	.dispclk_dppclk_vco_speed_mhz = 3600,
 	.xfc_bus_transport_time_us = 4,