Bluetooth: Add state to hci_chan

On an AMP controller, hci_chan maps to a logical link.  When a channel
is being moved, the logical link may or may not be connected already.
The hci_chan->state is used to determine the existance of a useable
logical link so the link can be either used or requested.

Signed-off-by: Mat Martineau <mathewm@codeaurora.org>
Acked-by: Marcel Holtmann <marcel@holtmann.org>
Acked-by: Andrei Emeltchenko <andrei.emeltchenko@intel.com>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>