perf/x86: Remove cpuc->enable check on Intl KNC event enable/disable

x86_pmu.enable() is called from x86_pmu_enable() with
cpuc->enabled set to 0.  This means we weren't re-enabling the
counters after a context switch.

This patch just removes the check, as it should't be necessary
(and the equivelent x86_ generic code does not have the checks).

The origin of this problem is the KNC driver being based on the
P6 one.   The P6 driver also has this issue, but works anyway
due to various lucky accidents.

Signed-off-by: Vince Weaver <vincent.weaver@maine.edu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Cc: eranian@gmail.com
Cc: Meadows
Cc: Lawrence F <lawrence.f.meadows@intel.com>
Link: http://lkml.kernel.org/r/alpine.DEB.2.02.1210171303290.23243@vincent-weaver-1.um.maine.edu
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/kernel/cpu/perf_event_knc.c

@@ -173,26 +173,22 @@ static void knc_pmu_enable_all(int added)
 static inline void
 knc_pmu_disable_event(struct perf_event *event)
 {
-	struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
 	struct hw_perf_event *hwc = &event->hw;
 	u64 val;
 
 	val = hwc->config;
-	if (cpuc->enabled)
-		val &= ~ARCH_PERFMON_EVENTSEL_ENABLE;
+	val &= ~ARCH_PERFMON_EVENTSEL_ENABLE;
 
 	(void)wrmsrl_safe(hwc->config_base + hwc->idx, val);
 }
 
 static void knc_pmu_enable_event(struct perf_event *event)
 {
-	struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
 	struct hw_perf_event *hwc = &event->hw;
 	u64 val;
 
 	val = hwc->config;
-	if (cpuc->enabled)
-		val |= ARCH_PERFMON_EVENTSEL_ENABLE;
+	val |= ARCH_PERFMON_EVENTSEL_ENABLE;
 
 	(void)wrmsrl_safe(hwc->config_base + hwc->idx, val);
 }