Core/Arena: Fix arena team existing name checking on team create

src/server/game/Battlegrounds/ArenaTeam.cpp

@@ -46,7 +46,7 @@ bool ArenaTeam::Create(uint64 captainGuid, uint8 type, std::string teamName, uin
         return false;
 
     // Check if arena team name is already taken
-    if (sArenaTeamMgr->GetArenaTeamByName(TeamName))
+    if (sArenaTeamMgr->GetArenaTeamByName(teamName))
         return false;
 
     // Generate new arena team id