Merge pull request swiftlang#9353 from hamishknight/rename-arg-interface-ty

[lldb] NFC: Update for `getArgumentInterfaceType` rename

Author: hamishknight

lldb/source/Plugins/TypeSystem/Swift/SwiftASTContext.cpp

@@ -611,7 +611,7 @@ class SwiftAllPayloadEnumDescriptor : public SwiftEnumDescriptor {
 
       swift::EnumElementDecl *case_decl = enum_case.decl;
       assert(case_decl);
-      auto arg_type = case_decl->getArgumentInterfaceType();
+      auto arg_type = case_decl->getPayloadInterfaceType();
       CompilerType case_type;
       if (arg_type) {
         case_type = ToCompilerType(