You're already capturing deadlock information in the system_health extended event session. You don't have to clutter up your error log with deadlock graphs through the traceflag if you don't want to. The only issue with this is that the output is in XML. However, here's a query[/url] to make that simple too.
"The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood"
- Theodore Roosevelt
Author of:
SQL Server Execution Plans
SQL Server Query Performance Tuning