drm/amd/display: add root clock control function pointer to fix display corruption

[Why and how]

External display has corruption because no root clock control function. Add the function pointer to fix the issue.
Reviewed-by: Daniel Miess <daniel.miess@amd.com>
Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Acked-by: Roman Li <roman.li@amd.com>
Signed-off-by: Xi (Alex) Liu <xi.liu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/hwss/dcn351/dcn351_init.c

@@ -145,6 +145,7 @@ static const struct hwseq_private_funcs dcn351_private_funcs = {
 	//.hubp_pg_control = dcn35_hubp_pg_control,
 	.enable_power_gating_plane = dcn35_enable_power_gating_plane,
 	.dpp_root_clock_control = dcn35_dpp_root_clock_control,
+	.dpstream_root_clock_control = dcn35_dpstream_root_clock_control,
 	.program_all_writeback_pipes_in_tree = dcn30_program_all_writeback_pipes_in_tree,
 	.update_odm = dcn35_update_odm,
 	.set_hdr_multiplier = dcn10_set_hdr_multiplier,