spirv: Remove subgroup id

src/shader_recompiler/backend/spirv/emit_spirv_warp.cpp

@@ -11,7 +11,7 @@ Id SubgroupScope(EmitContext& ctx) {
 }
 
 Id EmitWarpId(EmitContext& ctx) {
-    return ctx.OpLoad(ctx.U32[1], ctx.subgroup_id);
+    UNREACHABLE();
 }
 
 Id EmitLaneId(EmitContext& ctx) {

src/shader_recompiler/backend/spirv/spirv_emit_context.cpp

@@ -225,7 +225,6 @@ void EmitContext::DefineInputs(const Info& info) {
         break;
     }
     case Stage::Fragment:
-        subgroup_id = DefineVariable(U32[1], spv::BuiltIn::SubgroupId, spv::StorageClass::Input);
         subgroup_local_invocation_id = DefineVariable(
             U32[1], spv::BuiltIn::SubgroupLocalInvocationId, spv::StorageClass::Input);
         Decorate(subgroup_local_invocation_id, spv::Decoration::Flat);

src/shader_recompiler/backend/spirv/spirv_emit_context.h

@@ -180,7 +180,6 @@ public:
 
     Id workgroup_id{};
     Id local_invocation_id{};
-    Id subgroup_id{};
     Id subgroup_local_invocation_id{};
     Id image_u32{};