Revert "x86: do not use cpufreq_quick_get() for /proc/cpuinfo "cpu MHz""

This reverts commit 51204e0639c49ada02fd823782ad673b6326d748.

There wasn't really any good reason for it, and people are complaining
(rightly) that it broke existing practice.

Cc: Len Brown <len.brown@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/x86/kernel/cpu/proc.c

@@ -3,6 +3,7 @@
 #include <linux/timex.h>
 #include <linux/string.h>
 #include <linux/seq_file.h>
+#include <linux/cpufreq.h>
 
 /*
  *	Get CPU information for use by the procfs.
@@ -76,9 +77,14 @@ static int show_cpuinfo(struct seq_file *m, void *v)
 	if (c->microcode)
 		seq_printf(m, "microcode\t: 0x%x\n", c->microcode);
 
-	if (cpu_has(c, X86_FEATURE_TSC))
+	if (cpu_has(c, X86_FEATURE_TSC)) {
+		unsigned int freq = cpufreq_quick_get(cpu);
+
+		if (!freq)
+			freq = cpu_khz;
 		seq_printf(m, "cpu MHz\t\t: %u.%03u\n",
-			   cpu_khz / 1000, (cpu_khz % 1000));
+			   freq / 1000, (freq % 1000));
+	}
 
 	/* Cache size */
 	if (c->x86_cache_size >= 0)