[datapipe] Mark unfiltered datapipes as read only
[datapipe] Mark unfiltered datapipes as read only

The "read only" flag only means filter callbacks can't be installed to
the datapipe.

Mark datapipes that do not utilize filtering callbacks as READ_ONLY.

Signed-off-by: Simo Piiroinen <6d5e5360bed3d486f7d9fb26b0f737f7d4fd45ee@jollamobile.com>

spiiroin/mce,spiiroin/mce,spiiroin/mce,spiiroin/mce