softirq: Name hrtimer softirq also when CONFIG_HIGH_RES_TIMERS=n

Remy Bohmer pointed out that we create the hrtimer softirq thread even
when CONFIG_HIGH_RES_TIMERS is off. That results in a softirq-NULL
name for the thread. The thread is needed on -rt
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

kernel/softirq.c

@@ -1139,9 +1139,7 @@ static const char *softirq_names [] =
   [NET_RX_SOFTIRQ]	= "net-rx",
   [BLOCK_SOFTIRQ]	= "block",
   [TASKLET_SOFTIRQ]	= "tasklet",
-#ifdef CONFIG_HIGH_RES_TIMERS
   [HRTIMER_SOFTIRQ]	= "hrtimer",
-#endif
   [RCU_SOFTIRQ]		= "rcu",
 };