drm/amd/display: Fix nanosec stat overflow

[Why]
Nanosec stats can overflow on long running systems potentially causing
statistic logging issues.

[How]
Use 64bit types for nanosec stats to ensure no overflow.
Reviewed-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Aric Cyr <aric.cyr@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/modules/inc/mod_stats.h

@@ -57,10 +57,10 @@ void mod_stats_update_event(struct mod_stats *mod_stats,
 		unsigned int length);
 
 void mod_stats_update_flip(struct mod_stats *mod_stats,
-		unsigned long timestamp_in_ns);
+		unsigned long long timestamp_in_ns);
 
 void mod_stats_update_vupdate(struct mod_stats *mod_stats,
-		unsigned long timestamp_in_ns);
+		unsigned long long timestamp_in_ns);
 
 void mod_stats_update_freesync(struct mod_stats *mod_stats,
 		unsigned int v_total_min,