[rennes][abacus28] update pstate_driver

data/grid5000/sites/rennes/clusters/abacus28/nodes/abacus28-1.json

@@ -298,7 +298,7 @@
     "cstate_driver": "intel_idle",
     "cstate_governor": "menu",
     "ht_enabled": true,
-    "pstate_driver": "intel_cpufreq",
+    "pstate_driver": "intel_pstate",
     "pstate_governor": "performance",
     "turboboost_enabled": true
   },