Staging: lustre: make obd_device_cachep static

Variable obd_device_cachep is only used inside the file it is declared,
so it is better set as static
Signed-off-by: Pedro Marzo Perez <marzo.pedro@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lustre/obdclass/genops.c

@@ -45,7 +45,7 @@
 
 spinlock_t obd_types_lock;
 
-struct kmem_cache *obd_device_cachep;
+static struct kmem_cache *obd_device_cachep;
 struct kmem_cache *obdo_cachep;
 EXPORT_SYMBOL(obdo_cachep);
 static struct kmem_cache *import_cachep;