Fixes to Matrix 2 definition

MaterialGraphProject/Assets/UnityShaderEditor/Editor/Data/Nodes/Input/Matrix/Matrix2Node.cs

             var sb = new ShaderStringBuilder();
             if (!generationMode.IsPreview())
             {
-                sb.AppendLine("{0}3 _{1}_m0 = {0}3 ({2}, {3});", precision, GetVariableNameForNode(), 
+                sb.AppendLine("{0}2 _{1}_m0 = {0}2 ({2}, {3});", precision, GetVariableNameForNode(), 
-                sb.AppendLine("{0}3 _{1}_m1 = {0}3 ({2}, {3});", precision, GetVariableNameForNode(), 
+                sb.AppendLine("{0}2 _{1}_m1 = {0}2 ({2}, {3});", precision, GetVariableNameForNode(), 
                     NodeUtils.FloatToShaderValue(m_Row1.x), 
                     NodeUtils.FloatToShaderValue(m_Row1.y));
             }