crypto: chelsio - Fix NULL pointer dereference

Do not request FW to generate cidx update if there is less
space in tx queue to post new request.
SGE DBP 1 pidx increment too large
BUG: unable to handle kernel NULL pointer dereference at
0000000000000124
SGE error for queue 101
Signed-off-by: Atul Gupta <atul.gupta@chelsio.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/crypto/chelsio/chcr_ipsec.c

@@ -575,6 +575,7 @@ inline void *chcr_crypto_wreq(struct sk_buff *skb,
 	if (unlikely(credits < ETHTXQ_STOP_THRES)) {
 		netif_tx_stop_queue(q->txq);
 		q->q.stops++;
+		if (!q->dbqt)
 			wr_mid |= FW_WR_EQUEQ_F | FW_WR_EQUIQ_F;
 	}
 	wr_mid |= FW_ULPTX_WR_DATA_F;