powerpc/perf: Declare static identifier a such

There are three symbols (two variables and a function) that are being used
solely in the same file (imc-pmu.c), thus, these symbols should be static,
but they are not. This was detected by sparse:

	arch/powerpc/perf/imc-pmu.c:31:20: warning: symbol 'nest_imc_refc' was not declared. Should it be static?
	arch/powerpc/perf/imc-pmu.c:37:20: warning: symbol 'core_imc_refc' was not declared. Should it be static?
	arch/powerpc/perf/imc-pmu.c:46:16: warning: symbol 'imc_event_to_pmu' was not declared. Should it be static?

This patch simply adds the 'static' storage-class definition to these
symbols, thus, restricting their usage only in the imc-pmu.c file.
Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/perf/imc-pmu.c

@@ -28,13 +28,13 @@ static DEFINE_MUTEX(nest_init_lock);
 static DEFINE_PER_CPU(struct imc_pmu_ref *, local_nest_imc_refc);
 static struct imc_pmu **per_nest_pmu_arr;
 static cpumask_t nest_imc_cpumask;
-struct imc_pmu_ref *nest_imc_refc;
+static struct imc_pmu_ref *nest_imc_refc;
 static int nest_pmus;
 
 /* Core IMC data structures and variables */
 
 static cpumask_t core_imc_cpumask;
-struct imc_pmu_ref *core_imc_refc;
+static struct imc_pmu_ref *core_imc_refc;
 static struct imc_pmu *core_imc_pmu;
 
 /* Thread IMC data structures and variables */
@@ -43,7 +43,7 @@ static DEFINE_PER_CPU(u64 *, thread_imc_mem);
 static struct imc_pmu *thread_imc_pmu;
 static int thread_imc_mem_size;
 
-struct imc_pmu *imc_event_to_pmu(struct perf_event *event)
+static struct imc_pmu *imc_event_to_pmu(struct perf_event *event)
 {
 	return container_of(event->pmu, struct imc_pmu, pmu);
 }