cpufreq: speedstep: convert BUG() to BUG_ON()

To fix coccinelle WARNING.

WARNING: Use BUG_ON instead of if condition followed by BUG.
Signed-off-by: Yangtao Li <tiny.windzz@gmail.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

drivers/cpufreq/speedstep-ich.c

@@ -243,8 +243,7 @@ static unsigned int speedstep_get(unsigned int cpu)
 	unsigned int speed;
 
 	/* You're supposed to ensure CPU is online. */
-	if (smp_call_function_single(cpu, get_freq_data, &speed, 1) != 0)
-		BUG();
+	BUG_ON(smp_call_function_single(cpu, get_freq_data, &speed, 1));
 
 	pr_debug("detected %u kHz as current frequency\n", speed);
 	return speed;