UBUNTU: SAUCE: kaiser: fix perf crashes - fix to original commit

BugLink: http://bugs.launchpad.net/bugs/1741934

There was a back port of upstream 4.4 stable commit 20cbe9a3
to Xenial which failed remove a kfree() from release_ds_buffer().

This commit does only that.  It removes this extra kfree().  This left over
kfree was causing a kernel trace on many systems as reported in the bug.

This commit removes the kfree() like it should have been in the original commit.
Signed-off-by: Joseph Salisbury <joseph.salisbury@canonical.com>
Acked-by: Brad Figg brad.figg@canonical.com
Acked-by: Marcelo Henrique Cerri <marcelo.cerri@canonical.com>
Signed-off-by: Marcelo Henrique Cerri <marcelo.cerri@canonical.com>

arch/x86/events/intel/ds.c

@@ -415,7 +415,6 @@ static void release_ds_buffer(int cpu)
 		return;
 
 	per_cpu(cpu_hw_events, cpu).ds = NULL;
-	kfree(ds);
 }
 
 void release_ds_buffers(void)