firewire: expose extended tcode of incoming lock requests to (userspace) drivers

When a remote device does a LOCK_REQUEST, the core does not pass
the extended tcode to userspace.  This patch makes it use the
juju-specific tcodes listed in firewire-constants.h for incoming
requests.

Signed-off-by: Jay Fenlason <fenlason@redhat.com>

This matches how tcode in the API for outbound requests is treated.
Affects kernelspace and userspace drivers alike, but at the moment there
are no kernespace drivers that receive lock requests.

Split out from a combo patch, slightly reordered, changelog reworded.

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