RDMA/usnic: Fix remove address space warning

Sparse tool complains with the following error:
drivers/infiniband/hw/usnic/usnic_ib_main.c:445:16: warning: cast removes
	address space of expression

Fix it by doing casting on correct field and convert function helper which
sets ifaddr to be void, because there are no users who are interested in
returned value.

Fixes: c7845bcafe4d ("IB/usnic: Add UDP support in u*verbs.c, u*main.c and u*util.h")
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
diff --git a/drivers/infiniband/hw/usnic/usnic_ib_main.c b/drivers/infiniband/hw/usnic/usnic_ib_main.c
index e86700f9..f45e99a 100644
--- a/drivers/infiniband/hw/usnic/usnic_ib_main.c
+++ b/drivers/infiniband/hw/usnic/usnic_ib_main.c
@@ -351,7 +351,7 @@ static void *usnic_ib_device_add(struct pci_dev *dev)
 {
 	struct usnic_ib_dev *us_ibdev;
 	union ib_gid gid;
-	struct in_ifaddr *in;
+	struct in_device *ind;
 	struct net_device *netdev;
 
 	usnic_dbg("\n");
@@ -441,9 +441,11 @@ static void *usnic_ib_device_add(struct pci_dev *dev)
 	if (netif_carrier_ok(us_ibdev->netdev))
 		usnic_fwd_carrier_up(us_ibdev->ufdev);
 
-	in = ((struct in_device *)(netdev->ip_ptr))->ifa_list;
-	if (in != NULL)
-		usnic_fwd_add_ipaddr(us_ibdev->ufdev, in->ifa_address);
+	ind = in_dev_get(netdev);
+	if (ind->ifa_list)
+		usnic_fwd_add_ipaddr(us_ibdev->ufdev,
+				     ind->ifa_list->ifa_address);
+	in_dev_put(ind);
 
 	usnic_mac_ip_to_gid(us_ibdev->netdev->perm_addr,
 				us_ibdev->ufdev->inaddr, &gid.raw[0]);