Add gateway mode options to target hash

Summary:
We need to recompile if any of these change as they affect code generation.

Hopefully we will get a way to hash all the target options from Poplar
as a part of T43412 so we do not have to keep maintaining this here.

Fixes T43452.

Reviewers: #tensorflow, simonl, #framework_ip_review_-_any_oss_or_third-party_code_use_has_been_approved, vladimirm

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

Maniphest Tasks: T43452

Differential Revision: https://phabricator.sourcevertex.net/D49112

Author: hakos

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

@@ -2042,6 +2042,9 @@ Status PoplarExecutor::ConfigurePoplarDevice(const IpuOptions& cfg) {
       static_cast<int64>(ipu_.Target().getIpuLinkConfiguration()));
   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(
         std::hash<string>()(ipu_.Target().getTargetArchString()));