Remove unused variable binding to fix validate

(cherry picked from commit b7f51d60)

compiler/typecheck/TcPatSyn.lhs

@@ -321,8 +321,8 @@ tcCheckPatSynPat = go
     go1   (PArrPat pats _)    = mapM_ go pats
     go1   (ListPat pats _ _)  = mapM_ go pats
     go1   (TuplePat pats _ _) = mapM_ go pats
-    go1   (LitPat lit)        = return ()
-    go1   (NPat n _ _)        = return ()
+    go1   LitPat{}            = return ()
+    go1   NPat{}              = return ()
     go1   (SigPatIn pat _)    = go pat
     go1   (ViewPat _ pat _)   = go pat
     go1 p@SplicePat{}         = thInPatSynErr p