Bluetooth: Prevent buffer overflow for large advertisement data

There are some controllers sending out advertising data with illegal
length value which is longer than HCI_MAX_AD_LENGTH, causing the
buffer last_adv_data overflows. To avoid these controllers from
overflowing the buffer, we do not process the advertisement data
if its length is incorrect.

Signed-off-by: Chriz Chow <chriz.chow@aminocom.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>