Bluetooth: Keep msec in DISCOV_INTERLEAVED_TIMEOUT

Keep msec instead of jiffies in this define. This is needed by following
patch where we want this timeout to be exposed in debugfs.

Note: Value of this timeout comes from recommendation in BT Core Spec.4.0,
Vol 3, Part C, chapter 13.2.1.

Signed-off-by: Lukasz Rymanowski <lukasz.rymanowski@tieto.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>