staging: lustre: lustre: libcfs: define symbols as static

This patch fixes the following warning using sparse
- warning: symbol 'libcfs_debug_mb' was not declared. Should it be
  static?
- warning: symbol 'portal_enter_debugger' was not declared. Should
  it be static?
Signed-off-by: Chen Weixiang <weixiangx.chen@outlook.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lustre/libcfs/debug.c

@@ -57,7 +57,7 @@ module_param(libcfs_debug, int, 0644);
 MODULE_PARM_DESC(libcfs_debug, "Lustre kernel debug mask");
 EXPORT_SYMBOL(libcfs_debug);
 
-unsigned int libcfs_debug_mb = 0;
+static unsigned int libcfs_debug_mb;
 module_param(libcfs_debug_mb, uint, 0644);
 MODULE_PARM_DESC(libcfs_debug_mb, "Total debug buffer size.");
 EXPORT_SYMBOL(libcfs_debug_mb);
@@ -93,7 +93,7 @@ EXPORT_SYMBOL(libcfs_debug_binary);
 unsigned int libcfs_stack = 3 * THREAD_SIZE / 4;
 EXPORT_SYMBOL(libcfs_stack);
 
-unsigned int portal_enter_debugger;
+static unsigned int portal_enter_debugger;
 EXPORT_SYMBOL(portal_enter_debugger);
 
 unsigned int libcfs_catastrophe;