target-ppc: fix Book-E TLB matching

The Book-E TLB matching process should bail out early when a TLB
entry matches, but the access permissions are wrong. The CPU
will then raise a DSI error instead of a Data TLB error, as
described for TLB matching in Freescale and IBM documents.
Signed-off-by: NAlex Zuepke <azu@sysgo.de>
Signed-off-by: NDavid Gibson <david@gibson.dropbear.id.au>

target/ppc/mmu_helper.c

@@ -825,7 +825,7 @@ static int mmubooke_get_physical_address(CPUPPCState *env, mmu_ctx_t *ctx,
         tlb = &env->tlb.tlbe[i];
         ret = mmubooke_check_tlb(env, tlb, &raddr, &ctx->prot, address, rw,
                                  access_type, i);
-        if (!ret) {
+        if (ret != -1) {
             break;
         }
     }