net: xfrm: revert to lower xfrm dst gc limit

revert c386578f1cdb4dac230395 ("xfrm: Let the flowcache handle its size by default.").

Once we remove flow cache, we don't have a flow cache limit anymore.
We must not allow (virtually) unlimited allocations of xfrm dst entries.
Revert back to the old xfrm dst gc limits.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/xfrm4_policy.c b/net/ipv4/xfrm4_policy.c
index 71b4ecc1..19455a5 100644
--- a/net/ipv4/xfrm4_policy.c
+++ b/net/ipv4/xfrm4_policy.c
@@ -266,7 +266,7 @@ static struct dst_ops xfrm4_dst_ops_template = {
 	.destroy =		xfrm4_dst_destroy,
 	.ifdown =		xfrm4_dst_ifdown,
 	.local_out =		__ip_local_out,
-	.gc_thresh =		INT_MAX,
+	.gc_thresh =		32768,
 };
 
 static const struct xfrm_policy_afinfo xfrm4_policy_afinfo = {