[CPUFREQ] Clean up convoluted code in arch/x86/kernel/tsc.c:time_cpufreq_notifier()

Christoph Hellwig noticed the following potential uninitialised use:

 > arch/x86/kernel/tsc.c: In function 'time_cpufreq_notifier':
 > arch/x86/kernel/tsc.c:634: warning: 'dummy' may be used uninitialized in this function
 >
 > where we do have CONFIG_SMP set, freq->flags & CPUFREQ_CONST_LOOPS is
 > true and ref_freq is false.

It seems plausable, though the circumstances for hitting it are really low.
Nearly all SMP capable cpufreq drivers set CPUFREQ_CONST_LOOPS.
powernow-k8 is really the only exception. The older CPUs were typically
only ever UP. (powernow-k7 never supported SMP for eg)

It's worth fixing regardless, as it cleans up the code.

Fix possible uninitialized use of dummy, by just removing it,
and making the setting of lpj more obvious.

Signed-off-by: Dave Jones <davej@redhat.com>

arch/x86/kernel/tsc.c

@@ -631,17 +631,15 @@ static int time_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
 				void *data)
 {
 	struct cpufreq_freqs *freq = data;
-	unsigned long *lpj, dummy;
+	unsigned long *lpj;
 
 	if (cpu_has(&cpu_data(freq->cpu), X86_FEATURE_CONSTANT_TSC))
 		return 0;
 
-	lpj = &dummy;
-	if (!(freq->flags & CPUFREQ_CONST_LOOPS))
-#ifdef CONFIG_SMP
-		lpj = &cpu_data(freq->cpu).loops_per_jiffy;
-#else
 	lpj = &boot_cpu_data.loops_per_jiffy;
+#ifdef CONFIG_SMP
+	if (!(freq->flags & CPUFREQ_CONST_LOOPS))
+		lpj = &cpu_data(freq->cpu).loops_per_jiffy;
 #endif
 
 	if (!ref_freq) {