By THÉRÈSE MARGOLIS Thando Nomthandazo Mbokazi-Dlomo, wife of South African Ambassador to Mexico Dennis Thokozani Dlomo, was just named a semi-finalist in the Mrs. Royal International Pageant, a prestigious African beauty competition. Mbokazi-Dlomo, who last year was a finalist in the Mrs. South Africa competition, was selected as one of 31 Mrs. Royal International semi-finalists on Saturday, May 14. The