[clang] NFC: Remove duplicate DependentSizedMatrixType methods

Inherited from MatrixType.

Reviewed By: fhahn

Differential Revision: https://reviews.llvm.org/D109137

Author: c-rhodes

clang/include/clang/AST/Type.h

@@ -3524,14 +3524,10 @@ class DependentSizedMatrixType final : public MatrixType {
                            Expr *ColumnExpr, SourceLocation loc);
 
 public:
-  QualType getElementType() const { return ElementType; }
   Expr *getRowExpr() const { return RowExpr; }
   Expr *getColumnExpr() const { return ColumnExpr; }
   SourceLocation getAttributeLoc() const { return loc; }
 
-  bool isSugared() const { return false; }
-  QualType desugar() const { return QualType(this, 0); }
-
   static bool classof(const Type *T) {
     return T->getTypeClass() == DependentSizedMatrix;
   }