Bluetooth: Remove unnecessary queue_monitor_skb() function

Now that there's the general purpose hci_send_to_channel() API it will
do the exact same thing as queue_monitor_skb() when passed the monitor
HCI channel. This patch removes queue_monitor_skb() and replaces any
users of it with calls to hci_send_to_channel().

Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>