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.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>