powerpc/sparse: Make a bunch of things static

Squash a bunch of sparse warnings by making things static.

Reviewed-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
Signed-off-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
diff --git a/arch/powerpc/perf/power7-pmu.c b/arch/powerpc/perf/power7-pmu.c
index a383c23..7963658 100644
--- a/arch/powerpc/perf/power7-pmu.c
+++ b/arch/powerpc/perf/power7-pmu.c
@@ -416,7 +416,7 @@
 	NULL,
 };
 
-struct attribute_group power7_pmu_format_group = {
+static struct attribute_group power7_pmu_format_group = {
 	.name = "format",
 	.attrs = power7_pmu_format_attr,
 };