UAPI: Guard linux/pmu.h

Place reinclusion guards on linux/pmu.h otherwise the UAPI splitter won't
insert the #include to include the UAPI header from the kernel header.

Signed-off-by: David Howells <dhowells@redhat.com>
diff --git a/include/linux/pmu.h b/include/linux/pmu.h
index cafe98d..84e6a55 100644
--- a/include/linux/pmu.h
+++ b/include/linux/pmu.h
@@ -6,6 +6,8 @@
  * Copyright (C) 1998 Paul Mackerras.
  */
 
+#ifndef _LINUX_PMU_H
+#define _LINUX_PMU_H
 
 #define PMU_DRIVER_VERSION	2
 
@@ -207,3 +209,5 @@
 #endif
 
 #endif	/* __KERNEL__ */
+
+#endif /* _LINUX_PMU_H */