net: bpfilter: Fix type cast and pointer warnings

Fixes the following Sparse warnings:

net/bpfilter/bpfilter_kern.c:62:21: warning: cast removes address space
of expression
net/bpfilter/bpfilter_kern.c:101:49: warning: Using plain integer as
NULL pointer
Signed-off-by: NShanthosh RK <shanthosh.rk@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/bpfilter/bpfilter_kern.c

@@ -59,7 +59,7 @@ static int __bpfilter_process_sockopt(struct sock *sk, int optname,
 	req.is_set = is_set;
 	req.pid = current->pid;
 	req.cmd = optname;
-	req.addr = (long)optval;
+	req.addr = (long __force __user)optval;
 	req.len = optlen;
 	mutex_lock(&bpfilter_lock);
 	if (!info.pid)
@@ -98,7 +98,7 @@ static int __init load_umh(void)
 	pr_info("Loaded bpfilter_umh pid %d\n", info.pid);
 
 	/* health check that usermode process started correctly */
-	if (__bpfilter_process_sockopt(NULL, 0, 0, 0, 0) != 0) {
+	if (__bpfilter_process_sockopt(NULL, 0, NULL, 0, 0) != 0) {
 		stop_umh();
 		return -EFAULT;
 	}