Staging: lustre: Include header file that declares lprocfs_mdc_init_vars

This patch includes the header file mdc_internal.h that declares the
function lprocfs_mdc_init_vars.

This also eliminates the sparse warning:
warning: symbol 'lprocfs_mdc_init_vars' was not declared. Should it be static?

Signed-off-by: Darshana Padmadas <darshanapadmadas@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lustre/mdc/lproc_mdc.c

@@ -38,6 +38,7 @@
 #include <linux/vfs.h>
 #include "../include/obd_class.h"
 #include "../include/lprocfs_status.h"
+#include "mdc_internal.h"
 
 static int mdc_max_rpcs_in_flight_seq_show(struct seq_file *m, void *v)
 {