drbd: remove unused #include <linux/version.h>

Remove unused #include <linux/version.h>('s) in
  drivers/block/drbd/drbd_main.c
  drivers/block/drbd/drbd_receiver.c
  drivers/block/drbd/drbd_worker.c

Signed-off-by: Huang Weiyi <weiyi.huang@gmail.com>
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>

drivers/block/drbd/drbd_main.c

@@ -27,7 +27,6 @@
  */
 
 #include <linux/module.h>
-#include <linux/version.h>
 #include <linux/drbd.h>
 #include <asm/uaccess.h>
 #include <asm/types.h>

drivers/block/drbd/drbd_receiver.c

@@ -28,7 +28,6 @@
 #include <asm/uaccess.h>
 #include <net/sock.h>
 
-#include <linux/version.h>
 #include <linux/drbd.h>
 #include <linux/fs.h>
 #include <linux/file.h>

drivers/block/drbd/drbd_worker.c

@@ -24,7 +24,6 @@
  */
 
 #include <linux/module.h>
-#include <linux/version.h>
 #include <linux/drbd.h>
 #include <linux/sched.h>
 #include <linux/smp_lock.h>