Bluetooth: Fix calculation of SCO handle for packet processing

When processing SCO packets, the handle is wrongly assumed as 16-bit
value. The actual size is 12-bits and the other 4-bits are used for
packet flags.

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