powerpc/64s/radix: Do not allocate SLB shadow structures

These are unused in radix mode.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/kernel/paca.c

@@ -99,18 +99,27 @@ static inline void free_lppacas(void) { }
  * If you make the number of persistent SLB entries dynamic, please also
  * update PR KVM to flush and restore them accordingly.
  */
-static struct slb_shadow *slb_shadow;
+static struct slb_shadow * __initdata slb_shadow;
 
 static void __init allocate_slb_shadows(int nr_cpus, int limit)
 {
 	int size = PAGE_ALIGN(sizeof(struct slb_shadow) * nr_cpus);
+
+	if (early_radix_enabled())
+		return;
+
 	slb_shadow = __va(memblock_alloc_base(size, PAGE_SIZE, limit));
 	memset(slb_shadow, 0, size);
 }
 
 static struct slb_shadow * __init init_slb_shadow(int cpu)
 {
-	struct slb_shadow *s = &slb_shadow[cpu];
+	struct slb_shadow *s;
+
+	if (early_radix_enabled())
+		return NULL;
+
+	s = &slb_shadow[cpu];
 
 	/*
 	 * When we come through here to initialise boot_paca, the slb_shadow