Bluetooth: Update page scan parameters after successful write commands

The page scan parameters (interval, window and type) stored in struct
hci_dev should not only be updated after successful reads but also after
successful writes. This patch adds the necessary handlers for the write
command complete events and updates the stored values through them.

Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>