PPC MPC7544DS: Use new TLB helper function

Now that we have some nice helpers that can find us a TLB entry, let's
use that on the machine initialization code, so we don't need to know
about the internals of the TLB array.
Signed-off-by: NAlexander Graf <agraf@suse.de>

hw/ppce500_mpc8544ds.c

@@ -179,7 +179,7 @@ static void mmubooke_create_initial_mapping(CPUState *env,
                                      target_ulong va,
                                      target_phys_addr_t pa)
 {
-    ppcemb_tlb_t *tlb = &env->tlb[512].tlbe;
+    ppcemb_tlb_t *tlb = booke206_get_tlbe(env, 1, 0, 0);
 
     tlb->attr = 0;
     tlb->prot = PAGE_VALID | ((PAGE_READ | PAGE_WRITE | PAGE_EXEC) << 4);