Revert "llama : disable graph reuse with pipeline parallelism (#20463)"

This reverts commit 57819b8d4b.

src/llama-context.cpp

@@ -350,14 +350,6 @@ llama_context::llama_context(
 
         if (cparams.pipeline_parallel) {
             LLAMA_LOG_INFO("%s: pipeline parallelism enabled\n", __func__);
-
-            if (!graph_reuse_disable) {
-                // TODO: figure out a way to make graph reuse work with pipeline parallelism
-                // ref: https://github.com/ggml-org/llama.cpp/pull/20463
-                LLAMA_LOG_WARN("%s: graph reuse is currently not compatible with pipeline parallelism - disabling\n", __func__);
-
-                graph_reuse_disable = true;
-            }
         }
 
         sched_reserve();