drbd: use sched_setscheduler()

It was unnoticed for some time that assigning to current->policy is
no longer sufficient to set a real time priority for a kernel thread.

Reported-by: Charlie Suffin <Charlie.Suffin@stratus.com>
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/include/linux/drbd.h b/include/linux/drbd.h
index 3163307..1b4d4ee 100644
--- a/include/linux/drbd.h
+++ b/include/linux/drbd.h
@@ -52,7 +52,7 @@
 #endif
 
 extern const char *drbd_buildtag(void);
-#define REL_VERSION "8.4.2"
+#define REL_VERSION "8.4.3"
 #define API_VERSION 1
 #define PRO_VERSION_MIN 86
 #define PRO_VERSION_MAX 101