audioinjector-octo: Add continuous clock feature

audioinjector-octo: Add continuous clock feature

By user request, add a switch to prevent the clocks being stopped when
the stream is paused, stopped or shutdown. Provide access to the switch
by adding a 'non-stop-clocks' parameter to the audioinjector-addons
overlay.

See: https://github.com/raspberrypi/linux/issues/2409

Signed-off-by: Phil Elwell <phil@raspberrypi.org>
(cherry picked from commit 8eb4abd918a094dab50bab1b68fc4742ecea02f1
https://github.com/raspberrypi/linux raspi/rpi-4.15.y)
Signed-off-by: Paolo Pisati <paolo.pisati@canonical.com>
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>