[PATCH] powerpc/perf: Fix power_pmu_wants_prompt_pmi to be defined only for CONFIG_PPC64

[Athira Rajeev <atrajeev@linux.vnet.ibm.com>]

power_pmu_wants_prompt_pmi is used to decide if PMI should
be taken prompt. This is valid only for ppc64 and is used
in CONFIG_PPC_BOOK3S_64 context. Hence include the function
under config check for PPC64

Fixes warning for 32-bit compilation:

>> arch/powerpc/perf/core-book3s.c:2455:6: warning: no previous prototype for 'power_pmu_wants_prompt_pmi' [-Wmissing-prototypes]
    2455 | bool power_pmu_wants_prompt_pmi(void)
         |      ^~~~~~~~~~~~~~~~~~~~~~~~~~

Fixes: 5a7745b96f43 ("powerpc/64s/perf: add power_pmu_wants_prompt_pmi to say whether perf wants PMIs to be soft-NMI")
Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Reported-by: kernel test robot <lkp@intel.com>
---
Note: Address compilation warning reported here:
 https://lore.kernel.org/lkml/202112220137.X16y07Dp-lkp@intel.com/ 
Patch is based on powerpc/merge

 arch/powerpc/perf/core-book3s.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/powerpc/perf/core-book3s.c b/arch/powerpc/perf/core-book3s.c
index a684901b6965..b7160fae58c6 100644
--- a/arch/powerpc/perf/core-book3s.c
+++ b/arch/powerpc/perf/core-book3s.c
@@ -2452,6 +2452,7 @@ static void perf_event_interrupt(struct pt_regs *regs)
  * could possibly return false if only events are being counted rather than
  * samples being taken, but for now this is good enough.
  */
+#ifdef CONFIG_PPC64
 bool power_pmu_wants_prompt_pmi(void)
 {
 	struct cpu_hw_events *cpuhw;
@@ -2467,6 +2468,7 @@ bool power_pmu_wants_prompt_pmi(void)
 	cpuhw = this_cpu_ptr(&cpu_hw_events);
 	return cpuhw->n_events;
 }
+#endif
 
 static int power_pmu_prepare_cpu(unsigned int cpu)
 {
-- 
2.33.0