Valence Variations by B-Site Doping in A-Site Columnar-Ordered Quadruple Perovskites Sm2MnMn(Mn4–xTix)O12 with 1 ≤ x ≤ 3 (Valence Variations by B-Site Doping in A-Site Columnar-Ordered Quadruple Perovskites Sm2MnMn(Mn4-xTix)O12 with 1 <= x <= 3)