[XFRM] xfrm_policy_destroy: Rename and relative fixes.

Since __xfrm_policy_destroy is used to destory the resources
allocated by xfrm_policy_alloc. So using the name
__xfrm_policy_destroy is not correspond with xfrm_policy_alloc.
Rename it to xfrm_policy_destroy.

And along with some instances that call xfrm_policy_alloc
but not using xfrm_policy_destroy to destroy the resource,
fix them.

Signed-off-by: WANG Cong <xiyou.wangcong@gmail.com>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/xfrm.h b/include/net/xfrm.h
index a419a43..5ebb9ba 100644
--- a/include/net/xfrm.h
+++ b/include/net/xfrm.h
@@ -626,12 +626,12 @@
 		atomic_inc(&policy->refcnt);
 }
 
-extern void __xfrm_policy_destroy(struct xfrm_policy *policy);
+extern void xfrm_policy_destroy(struct xfrm_policy *policy);
 
 static inline void xfrm_pol_put(struct xfrm_policy *policy)
 {
 	if (atomic_dec_and_test(&policy->refcnt))
-		__xfrm_policy_destroy(policy);
+		xfrm_policy_destroy(policy);
 }
 
 #ifdef CONFIG_XFRM_SUB_POLICY