liquidio: fix Smatch error

Fix Smatch error by not dereferencing iq pointer if it's NULL.

See http://marc.info/?l=kernel-janitors&m=150296723301129&w=2

Also, remove unnecessary parentheses.

Fixes: d314ac222829 ("liquidio: moved liquidio_napi_poll to lio_core.c")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Intiyaz Basha <intiyaz.basha@cavium.com>
Signed-off-by: Felix Manlunas <felix.manlunas@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/cavium/liquidio/lio_core.c

@@ -668,8 +668,8 @@ static int liquidio_napi_poll(struct napi_struct *napi, int budget)
 
 #define MAX_REG_CNT  2000000U
 	/* force enable interrupt if reg cnts are high to avoid wraparound */
-	if (((work_done < budget) && (tx_done)) ||
-	    (iq->pkt_in_done >= MAX_REG_CNT) ||
+	if ((work_done < budget && tx_done) ||
+	    (iq && iq->pkt_in_done >= MAX_REG_CNT) ||
 	    (droq->pkt_count >= MAX_REG_CNT)) {
 		tx_done = 1;
 		napi_complete_done(napi, work_done);