perf/x86: Fixup typo in stub functions

perf/x86: Fixup typo in stub functions

Guenter reported a build warning for CONFIG_CPU_SUP_INTEL=n:

  > With allmodconfig-CONFIG_CPU_SUP_INTEL, this patch results in:
  >
  > In file included from arch/x86/events/amd/core.c:8:0:
  > arch/x86/events/amd/../perf_event.h:1036:45: warning: ‘struct cpu_hw_event’ declared inside parameter list will not be visible outside of this definition or declaration
  >  static inline int intel_cpuc_prepare(struct cpu_hw_event *cpuc, int cpu)

While harmless (an unsed pointer is an unused pointer, no matter the type)
it needs fixing.

Reported-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Fixes: d01b1f96a82e ("perf/x86/intel: Make cpuc allocations consistent")
Link: http://lkml.kernel.org/r/20190315081410.GR5996@hirez.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>