cxgb4: Fix queue free path of ULD drivers

Setting sge_uld_rxq_info to NULL in free_queues_uld().
We are referencing sge_uld_rxq_info in cxgb_up(). This
will fix a panic when interface is brought up after a
ULDq creation failure.

Fixes: 94cdb8bb (cxgb4: Add support for dynamic allocation
       of resources for ULD)
Signed-off-by: Arjun Vynipadath <arjun@chelsio.com>
Signed-off-by: Casey Leedom <leedom@chelsio.com>
Signed-off-by: Ganesh Goudhar <ganeshgr@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/chelsio/cxgb4/cxgb4_uld.c

@@ -342,6 +342,7 @@ static void free_queues_uld(struct adapter *adap, unsigned int uld_type)
 {
 	struct sge_uld_rxq_info *rxq_info = adap->sge.uld_rxq_info[uld_type];
 
+	adap->sge.uld_rxq_info[uld_type] = NULL;
 	kfree(rxq_info->rspq_id);
 	kfree(rxq_info->uldrxq);
 	kfree(rxq_info);