Bluetooth: Add helper to get HCI channel of a socket

We'll need to have access to which HCI channel a socket is bound to, in
order to manage pending mgmt commands in clean way. This patch adds a
helper for the purpose.

Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
diff --git a/include/net/bluetooth/bluetooth.h b/include/net/bluetooth/bluetooth.h
index d871ba3..33a5e00 100644
--- a/include/net/bluetooth/bluetooth.h
+++ b/include/net/bluetooth/bluetooth.h
@@ -338,6 +338,7 @@
 void hci_sock_set_flag(struct sock *sk, int nr);
 void hci_sock_clear_flag(struct sock *sk, int nr);
 int hci_sock_test_flag(struct sock *sk, int nr);
+unsigned short hci_sock_get_channel(struct sock *sk);
 
 int hci_sock_init(void);
 void hci_sock_cleanup(void);