perf/x86/amd: Remove set but not used variable 'active'

'-Wunused-but-set-variable' triggers this warning:

  arch/x86/events/amd/core.c: In function amd_pmu_handle_irq:
  arch/x86/events/amd/core.c:656:6: warning: variable active set but not used [-Wunused-but-set-variable]

GCC is right, 'active' is not used anymore.

This variable was introduced earlier this year and then removed in:

  df4d2973 perf/x86/amd: Change/fix NMI latency mitigation to use a timestamp

[ mingo: Improved the changelog, fixed build warning caused by this fix, improved surrounding code. ]
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Zheng Yongjun <zhengyongjun3@huawei.com>
Cc: <acme@kernel.org>
Cc: <alexander.shishkin@linux.intel.com>
Cc: <mark.rutland@arm.com>
Cc: <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20191110094453.113001-1-zhengyongjun3@huawei.comSigned-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/events/amd/core.c

@@ -652,15 +652,7 @@ static void amd_pmu_disable_event(struct perf_event *event)
  */
 static int amd_pmu_handle_irq(struct pt_regs *regs)
 {
-	struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
-	int active, handled;
-
-	/*
-	 * Obtain the active count before calling x86_pmu_handle_irq() since
-	 * it is possible that x86_pmu_handle_irq() may make a counter
-	 * inactive (through x86_pmu_stop).
-	 */
-	active = __bitmap_weight(cpuc->active_mask, X86_PMC_IDX_MAX);
+	int handled;
 
 	/* Process any counter overflows */
 	handled = x86_pmu_handle_irq(regs);
@@ -670,8 +662,7 @@ static int amd_pmu_handle_irq(struct pt_regs *regs)
 	 * NMIs will be claimed if arriving within that window.
 	 */
 	if (handled) {
-		this_cpu_write(perf_nmi_tstamp,
-			       jiffies + perf_nmi_window);
+		this_cpu_write(perf_nmi_tstamp, jiffies + perf_nmi_window);
 
 		return handled;
 	}