x86, sched: Fix undefined reference to init_freq_invariance_cppc() build error

The init_freq_invariance_cppc function is implemented in smpboot and depends on
CONFIG_SMP.

  MODPOST vmlinux.symvers
  MODINFO modules.builtin.modinfo
  GEN     modules.builtin
  LD      .tmp_vmlinux.kallsyms1
ld: drivers/acpi/cppc_acpi.o: in function `acpi_cppc_processor_probe':
/home/ray/brahma3/linux/drivers/acpi/cppc_acpi.c:819: undefined reference to `init_freq_invariance_cppc'
make: *** [Makefile:1161: vmlinux] Error 1

See https://lore.kernel.org/lkml/484af487-7511-647e-5c5b-33d4429acdec@infradead.org/.

Fixes: 41ea6672 ("x86, sched: Calculate frequency invariance for AMD systems")
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Huang Rui <ray.huang@amd.com>
[ rjw: Subject edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

arch/x86/include/asm/topology.h

@@ -221,7 +221,7 @@ static inline void arch_set_max_freq_ratio(bool turbo_disabled)
 }
 #endif
 
-#ifdef CONFIG_ACPI_CPPC_LIB
+#if defined(CONFIG_ACPI_CPPC_LIB) && defined(CONFIG_SMP)
 void init_freq_invariance_cppc(void);
 #define init_freq_invariance_cppc init_freq_invariance_cppc
 #endif