rcu: Remove self-stack-trace when all quiescent states seen

When all quiescent states have been seen, it is normally the grace-period
kthread that is in trouble.  Although the existing stack trace from
the current CPU might possibly provide useful information, experience
indicates that there is too much noise for this to be worthwhile.

This commit therefore removes this stack trace from the output.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

kernel/rcu/tree_stall.h

@@ -440,8 +440,6 @@ static void print_other_cpu_stall(unsigned long gp_seq)
 			       rcu_state.name, j - gpa, j, gpa,
 			       READ_ONCE(jiffies_till_next_fqs),
 			       rcu_get_root()->qsmask);
-			/* In this case, the current CPU might be at fault. */
-			sched_show_task(current);
 		}
 	}
 	/* Rewrite if needed in case of slow consoles. */