staging: lustre: reapply an older patch that was reverted

This reapplies part of 9edf0f67 (staging:
lustre: clean up format string usages) as it was reverted in a recent
change to this file.

That proves the big problem of having external trees you have to have
patches flowing back into them from upstream or things break down...
Reported-by: Kees Cook <keescook@chromium.org>
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Cc: Peng Tao <bergwolf@gmail.com>
Cc: Andreas Dilger <andreas.dilger@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lustre/ptlrpc/ptlrpcd.c

@@ -636,7 +636,7 @@ int ptlrpcd_start(int index, int max, const char *name, struct ptlrpcd_ctl *pc)
 				GOTO(out_env, rc);
 		}
 
-		task = kthread_run(ptlrpcd, pc, pc->pc_name);
+		task = kthread_run(ptlrpcd, pc, "%s", pc->pc_name);
 		if (IS_ERR(task))
 			GOTO(out_env, rc = PTR_ERR(task));