[IPSEC] xfrm_user: Kill PAGE_SIZE check in verify_sec_ctx_len()

First, it warns when PAGE_SIZE >= 64K because the ctx_len
field is 16-bits.

Secondly, if there are any real length limitations it can
be verified by the security layer security_xfrm_state_alloc()
call.

Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
index 07b7168..7b1acd9 100644
--- a/net/xfrm/xfrm_user.c
+++ b/net/xfrm/xfrm_user.c
@@ -101,9 +101,6 @@
 
 	uctx = RTA_DATA(rt);
 
-	if (uctx->ctx_len > PAGE_SIZE)
-		return -EINVAL;
-
 	len += sizeof(struct xfrm_user_sec_ctx);
 	len += uctx->ctx_len;