Remove multiReadST from gateway target options

Summary:
Removed option from poplar, the better solution is T43412, but for now this fixes the build

Ref T43366

Test Plan: Builds on CI

Reviewers: georgep, #tensorflow, #framework_ip_review_-_any_oss_or_third-party_code_use_has_been_approved, jakeh

Reviewed By: #tensorflow, #framework_ip_review_-_any_oss_or_third-party_code_use_has_been_approved, jakeh

Maniphest Tasks: T43366

Differential Revision: https://phabricator.sourcevertex.net/D52617

Author: samloescher

tensorflow/compiler/plugin/poplar/driver/poplar_executor.cc

@@ -2044,7 +2044,6 @@ Status PoplarExecutor::ConfigurePoplarDevice(const IpuOptions& cfg) {
   target_hash.push_back(ipu_.Target().getIpuLinkDomainSize());
   target_hash.push_back(static_cast<int64>(ipu_.Target().getIpuLinkTopology()));
   target_hash.push_back(ipu_.Target().getGatewayMode());
-  target_hash.push_back(ipu_.Target().getGatewayMultiReadServiceTable());
 
   if (ipu_.Target().getTargetType() == poplar::TargetType::IPU) {
     target_hash.push_back(