powerpc: Fix STAB initialization

Commit f5339277 accidentally removed
more than just iSeries bits and took out the call to stab_initialize()
thus breaking support for POWER3 processors.

Put it back. (Yes, nobody noticed until now ...)
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
CC: <stable@vger.kernel.org> [v3.4+]

arch/powerpc/mm/hash_utils_64.c

@@ -759,6 +759,8 @@ void __init early_init_mmu(void)
 	/* Initialize stab / SLB management */
 	if (mmu_has_feature(MMU_FTR_SLB))
 		slb_initialize();
+	else
+		stab_initialize(get_paca()->stab_real);
 }
 
 #ifdef CONFIG_SMP