powerpc/pmac/smp: Avoid unused-variable warnings

When building with ppc64_defconfig, the compiler reports
that these 2 variables are not used:
    warning: unused variable 'core99_l2_cache' [-Wunused-variable]
    warning: unused variable 'core99_l3_cache' [-Wunused-variable]

They are only used when CONFIG_PPC64 is not defined. Move
them into a section which does the same macro check.
Reported-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Ilie Halip <ilie.halip@gmail.com>
[mpe: Move them into core99_init_caches() which is their only user]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190920153951.25762-1-ilie.halip@gmail.com

arch/powerpc/platforms/powermac/smp.c

@@ -660,13 +660,13 @@ static void smp_core99_gpio_tb_freeze(int freeze)
 
 #endif /* !CONFIG_PPC64 */
 
-/* L2 and L3 cache settings to pass from CPU0 to CPU1 on G4 cpus */
-volatile static long int core99_l2_cache;
-volatile static long int core99_l3_cache;
-
 static void core99_init_caches(int cpu)
 {
 #ifndef CONFIG_PPC64
+	/* L2 and L3 cache settings to pass from CPU0 to CPU1 on G4 cpus */
+	volatile static long int core99_l2_cache;
+	volatile static long int core99_l3_cache;
+
 	if (!cpu_has_feature(CPU_FTR_L2CR))
 		return;