[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/net/key/af_key.c b/net/key/af_key.c
index 76dcd88..16b72b5 100644
--- a/net/key/af_key.c
+++ b/net/key/af_key.c
@@ -2291,8 +2291,7 @@
 	return 0;
 
 out:
-	security_xfrm_policy_free(xp);
-	kfree(xp);
+	xfrm_policy_destroy(xp);
 	return err;
 }
 
@@ -3236,8 +3235,7 @@
 	return xp;
 
 out:
-	security_xfrm_policy_free(xp);
-	kfree(xp);
+	xfrm_policy_destroy(xp);
 	return NULL;
 }