[X25]: Avoid divides and sparse warnings

   CHECK   net/x25/af_x25.c
net/x25/af_x25.c:117:46: warning: expensive signed divide
   CHECK   net/x25/x25_facilities.c
net/x25/x25_facilities.c:209:30: warning: expensive signed divide
   CHECK   net/x25/x25_in.c
net/x25/x25_in.c:250:26: warning: expensive signed divide
   CHECK   net/x25/x25_proc.c
net/x25/x25_proc.c:48:11: warning: context imbalance in 'x25_seq_route_start'
- wrong count at exit
net/x25/x25_proc.c:72:13: warning: context imbalance in 'x25_seq_route_stop' -
unexpected unlock
net/x25/x25_proc.c:112:11: warning: context imbalance in
'x25_seq_socket_start' - wrong count at exit
net/x25/x25_proc.c:129:13: warning: context imbalance in 'x25_seq_socket_stop'
- unexpected unlock
net/x25/x25_proc.c:190:11: warning: context imbalance in
'x25_seq_forward_start' - wrong count at exit
net/x25/x25_proc.c:215:13: warning: context imbalance in
'x25_seq_forward_stop' - unexpected unlock
   CHECK   net/x25/x25_subr.c
net/x25/x25_subr.c:362:57: warning: expensive signed divide

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/x25/x25_subr.c b/net/x25/x25_subr.c
index 8d6220a..511a598 100644
--- a/net/x25/x25_subr.c
+++ b/net/x25/x25_subr.c
@@ -359,7 +359,7 @@
 {
 	struct x25_sock *x25 = x25_sk(sk);
 
-	if (atomic_read(&sk->sk_rmem_alloc) < (sk->sk_rcvbuf / 2) &&
+	if (atomic_read(&sk->sk_rmem_alloc) < (sk->sk_rcvbuf >> 1) &&
 	    (x25->condition & X25_COND_OWN_RX_BUSY)) {
 		x25->condition &= ~X25_COND_OWN_RX_BUSY;
 		x25->condition &= ~X25_COND_ACK_PENDING;