Bluetooth: btbcm: disable read tx power for MacBook Air 8,1 and 8,2

The MacBook Air 8,1 and 8,2 also need querying of LE Tx power
to be disabled for Bluetooth to work.

Signed-off-by: Aditya Garg <gargaditya08@live.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Cc: stable@vger.kernel.org