powerpc: Fix crash on CPU hotplug

early_init_mmu_secondary() is called at CPU hotplug time, so it
must be marked as __cpuinit, not __init.

Caused by 757c74d2 ("powerpc/mm: Introduce early_init_mmu() on 64-bit").
Tested-by: Sachin Sant <sachinp@in.ibm.com>
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/mm/hash_utils_64.c

@@ -753,7 +753,7 @@ void __init early_init_mmu(void)
 }
 
 #ifdef CONFIG_SMP
-void __init early_init_mmu_secondary(void)
+void __cpuinit early_init_mmu_secondary(void)
 {
 	/* Initialize hash table for that CPU */
 	if (!firmware_has_feature(FW_FEATURE_LPAR))