Bluetooth: Do not send data during channel move

Outgoing ERTM data is queued during a channel move.  The ERTM state
machine is partially reset at the start of a move, and must be
resynchronized with the remote state machine at the end of the move.
Data is not sent so that there are no state transitions between the
partial reset and the resync.

Streaming mode frames are dropped during a move.

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>