firewire: new stack is no longer experimental

The new stack is now recommended over the old one if used for industrial
video (IIDC/DCAM) or for storage devices (SBP-2) due to better
performance, improved compatibility, added features, and security.  It
should also be functionally on par with and is more secure than the old
ieee1394 stack in the use case of consumer video devices.

IP-over-1394 support for the new stack is currently emerging, and a
backend of the firedtv DVB driver to the new stack should be available
soon.

The one remaining area where the old stack is still required are audio
devices, as the new stack is not yet able to support the FFADO FireWire
audio framework.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>