In some situations you need to set the compress param without an
algorithm. Compression will be turned off, but the packet framing for
compression will still be enabled, allowing a different setting to be
pushed later.
As it is not possible to have options with optional values at the
moment, I've introduced a pseudo value "frames_only" which will be
removed in the init script.
Signed-off-by: Martin Schiller <ms@dev.tdt.de>