[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_in.c b/net/x25/x25_in.c
index 1c88762..7d7c3ab 100644
--- a/net/x25/x25_in.c
+++ b/net/x25/x25_in.c
@@ -247,7 +247,7 @@
 					break;
 				}
 				if (atomic_read(&sk->sk_rmem_alloc) >
-				    (sk->sk_rcvbuf / 2))
+				    (sk->sk_rcvbuf >> 1))
 					x25->condition |= X25_COND_OWN_RX_BUSY;
 			}
 			/*