[fuchsia] use ssh key built by jiri hook

Change-Id: Ibeb2e321543a69daaf258095cb2a75f2212a74ae
diff --git a/fuchsia/developer-keys/BUILD.gn b/fuchsia/developer-keys/BUILD.gn
index e095267..93b19ff 100644
--- a/fuchsia/developer-keys/BUILD.gn
+++ b/fuchsia/developer-keys/BUILD.gn
@@ -71,7 +71,7 @@
   config_file = "${keys_dir}/ssh_config"
   script = "generate_ssh_config.sh"
   args = [
-    rebase_path("${keys_dir}/id_ed25519"),
+    rebase_path("//.ssh/pkey"),
     rebase_path(config_file),
   ]
   outputs = [