Bluetooth: Don't send device found events for duplicate reports

Occasionally, during active scanning we will receive duplicate ADV_IND
reports from the same device before receiving the SCAN_RSP from them. In
order to not wake up user space unnecessarily it's better not to send
these extra events as they do not contain any new information.

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