staging: lustre: mdc: remove unneeded null test before free

Kfree can cope with a null argument, so drop null tests.

The semantic patch that makes this change is as follows:
(http://coccinelle.lip6.fr/)

// <smpl>
@@ expression ptr; @@

- if (ptr != NULL)
  kfree(ptr);
// </smpl>
Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lustre/mdc/mdc_request.c

@@ -1644,8 +1644,7 @@ static int mdc_changelog_send_thread(void *csdata)
 		llog_cat_close(NULL, llh);
 	if (ctxt)
 		llog_ctxt_put(ctxt);
-	if (cs->cs_buf)
-		kfree(cs->cs_buf);
+	kfree(cs->cs_buf);
 	kfree(cs);
 	return rc;
 }