Staging: silicom: fix dangerous if condition in bpctl_mod.c

checkpatch script returns the following warning:
ERROR: do not use assignment in if condition
+                       if (((dev_num = get_dev_idx(dev->ifindex)) ==
            -1) |

This patch fixes the if condition by splitting it.
Signed-off-by: Neil Armstrong <superna9999@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/silicom/bpctl_mod.c

@@ -219,8 +219,12 @@ static int bp_device_event(struct notifier_block *unused,
 			if (netif_carrier_ok(dev))
 				return NOTIFY_DONE;
 
-			if (((dev_num = get_dev_idx(dev->ifindex)) == -1) ||
-			    (!(pbpctl_dev = &bpctl_dev_arr[dev_num])))
+			dev_num = get_dev_idx(dev->ifindex);
+			if (dev_num == -1)
+				return NOTIFY_DONE;
+
+			pbpctl_dev = &bpctl_dev_arr[dev_num];
+			if (!pbpctl_dev)
 				return NOTIFY_DONE;
 
 			if ((is_bypass_fn(pbpctl_dev)) == 1)