Bluetooth: HCI: Use skb_pull_data to parse LE Advertising Report event

This uses skb_pull_data to check the LE Advertising Report events
received have the minimum required length.

Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>