Bluetooth: Split hci_update_page_scan into two functions

To keep the parameter list and its semantics clear it makes sense to
split the hci_update_page_scan function into two separate functions: one
taking a hci_dev and another taking a hci_request. The one taking a
hci_dev constructs its own hci_request and then calls the other
function.

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