intel_pstate: Fix "performance" mode behavior with HWP enabled

If hardware-driven P-state selection (HWP) is enabled, the
"performance" mode of intel_pstate should only allow the processor
to use the highest-performance P-state available.  That is not
the case currently, so make it actually happen.
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Alexandra Yates <alexandra.yates@linux.intel.com>
[ rjw: Subject and changelog ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/cpufreq/intel_pstate.c

@@ -1101,6 +1101,8 @@ static int intel_pstate_set_policy(struct cpufreq_policy *policy)
 	    policy->max >= policy->cpuinfo.max_freq) {
 		pr_debug("intel_pstate: set performance\n");
 		limits = &performance_limits;
+		if (hwp_active)
+			intel_pstate_hwp_set();
 		return 0;
 	}