[Bluetooth] Add support for TIOCOUTQ and TIOCINQ ioctls

Almost every protocol family supports the TIOCOUTQ and TIOCINQ ioctls
and even Bluetooth could make use of them. When implementing audio
streaming and integration with GStreamer or PulseAudio they will allow
a better timing and synchronization.

Signed-off-by: Marcel Holtmann <marcel@holtmann.org>