staging: lustre: obdclass: Remove duplicate header file inclusion

Removed the header file included twice.
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lustre/obdclass/linux/linux-sysctl.c

@@ -38,7 +38,6 @@
 #include <linux/sysctl.h>
 #include <linux/sched.h>
 #include <linux/mm.h>
-#include <linux/sysctl.h>
 #include <linux/proc_fs.h>
 #include <linux/slab.h>
 #include <linux/stat.h>