cpufreq: intel_pstate: Fix invalid EPB setting

The max value of EPB can only be 0x0F. Attempting to set more than that
triggers an "unchecked MSR access error" warning which happens in
intel_pstate_hwp_force_min_perf() called via cpufreq stop_cpu().

However, it is not even necessary to touch the EPB from intel_pstate,
because it is restored on every CPU online by the intel_epb.c code,
so let that code do the right thing and drop the redundant (and
incorrect) EPB update from intel_pstate.

Fixes: af3b7379 ("cpufreq: intel_pstate: Force HWP min perf before offline")
Reported-by: Qian Cai <cai@lca.pw>
Cc: 5.2+ <stable@vger.kernel.org> # 5.2+
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
[ rjw: Changelog ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/cpufreq/intel_pstate.c

@@ -847,11 +847,9 @@ static void intel_pstate_hwp_force_min_perf(int cpu)
 	value |= HWP_MAX_PERF(min_perf);
 	value |= HWP_MIN_PERF(min_perf);
 
-	/* Set EPP/EPB to min */
+	/* Set EPP to min */
 	if (boot_cpu_has(X86_FEATURE_HWP_EPP))
 		value |= HWP_ENERGY_PERF_PREFERENCE(HWP_EPP_POWERSAVE);
-	else
-		intel_pstate_set_epb(cpu, HWP_EPP_BALANCE_POWERSAVE);
 
 	wrmsrl_on_cpu(cpu, MSR_HWP_REQUEST, value);
 }