acpi-cpufreq: fix a memleak when unloading driver

We didn't free per_cpu(acfreq_data, cpu)->freq_table
when acpi_freq driver is unloaded.

Resulting in the following messages in /sys/kernel/debug/kmemleak:

unreferenced object 0xf6450e80 (size 64):
  comm "modprobe", pid 1066, jiffies 4294677317 (age 19290.453s)
  hex dump (first 32 bytes):
    00 00 00 00 e8 a2 24 00 01 00 00 00 00 9f 24 00  ......$.......$.
    02 00 00 00 00 6a 18 00 03 00 00 00 00 35 0c 00  .....j.......5..
  backtrace:
    [<c123ba97>] kmemleak_alloc+0x27/0x50
    [<c109f96f>] __kmalloc+0xcf/0x110
    [<f9da97ee>] acpi_cpufreq_cpu_init+0x1ee/0x4e4 [acpi_cpufreq]
    [<c11cd8d2>] cpufreq_add_dev+0x142/0x3a0
    [<c11920b7>] sysdev_driver_register+0x97/0x110
    [<c11cce56>] cpufreq_register_driver+0x86/0x140
    [<f9dad080>] 0xf9dad080
    [<c1001130>] do_one_initcall+0x30/0x160
    [<c10626e9>] sys_init_module+0x99/0x1e0
    [<c1002d97>] sysenter_do_call+0x12/0x26
    [<ffffffff>] 0xffffffff

https://bugzilla.kernel.org/show_bug.cgi?id=15807#c21

Tested-by: Toralf Forster <toralf.foerster@gmx.de>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>

arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c

@@ -701,6 +701,7 @@ static int acpi_cpufreq_cpu_exit(struct cpufreq_policy *policy)
 		per_cpu(acfreq_data, policy->cpu) = NULL;
 		acpi_processor_unregister_performance(data->acpi_data,
 						      policy->cpu);
+		kfree(data->freq_table);
 		kfree(data);
 	}