fix reading host.fw through IPCC interface

fix reading host.fw through IPCC interface

IPCC has no knowledge about FUSE based links, but we used
'local/host.fw' here, where local is always a link to
'nodes/<LOCAL-NODENAME>/', this works only when using the common file
system interface provided by FUSE, but not if we're talking directly
with our memdb file store through IPCC..

So use a nodename based path here, to avoid getting just empty
strings for host.fw.

fixes commit 0dbef53046fade02efec143d3b7a0f4f9021b618

Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>