ceph: clean up header guards

Signed-off-by: Sage Weil <sage@newdream.net>
diff --git a/fs/ceph/ceph_hash.h b/fs/ceph/ceph_hash.h
index 5ac470c..d099c3f 100644
--- a/fs/ceph/ceph_hash.h
+++ b/fs/ceph/ceph_hash.h
@@ -1,5 +1,5 @@
-#ifndef _FS_CEPH_HASH_H
-#define _FS_CEPH_HASH_H
+#ifndef FS_CEPH_HASH_H
+#define FS_CEPH_HASH_H
 
 #define CEPH_STR_HASH_LINUX      0x1  /* linux dcache hash */
 #define CEPH_STR_HASH_RJENKINS   0x2  /* robert jenkins' */