KVM: PPC: Book3E: Unlock mmu_lock when setting caching atttribute

The patch 08c9a188
  	kvm: powerpc: use caching attributes as per linux pte
do not handle properly the error case, letting mmu_lock locked. The lock
will further generate a RCU stall from kvmppc_e500_emul_tlbwe() caller.

In case of an error go to out label.
Signed-off-by: Mihai Caraman <mihai.caraman@freescale.com>
Signed-off-by: Alexander Graf <agraf@suse.de>

arch/powerpc/kvm/e500_mmu_host.c

@@ -473,7 +473,8 @@ static inline int kvmppc_e500_shadow_map(struct kvmppc_vcpu_e500 *vcpu_e500,
 		if (printk_ratelimit())
 			pr_err("%s: pte not present: gfn %lx, pfn %lx\n",
 				__func__, (long)gfn, pfn);
-		return -EINVAL;
+		ret = -EINVAL;
+		goto out;
 	}
 	kvmppc_e500_ref_setup(ref, gtlbe, pfn, wimg);