[WebAssembly] Remove dead declaration MatchTableForLowering

The corresponding function definition was removed on Sep 27, 2022 in
commit 1bd1a44.

Author: kazutakahirata

llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.h

@@ -140,11 +140,6 @@ class WebAssemblyTargetLowering final : public TargetLowering {
   SDValue LowerLoad(SDValue Op, SelectionDAG &DAG) const;
   SDValue LowerStore(SDValue Op, SelectionDAG &DAG) const;
 
-  // Helper for LoadLoad and LowerStore
-  bool MatchTableForLowering(SelectionDAG &DAG, const SDLoc &DL,
-                             const SDValue &Base, GlobalAddressSDNode *&GA,
-                             SDValue &Idx) const;
-
   // Custom DAG combine hooks
   SDValue
   PerformDAGCombine(SDNode *N,