fabric_name is one of many fc_host attributes in Linux that is optional
and left to the low-level driver to decide if it is implemented.
The zfcp device driver does not provide a fabric name for an fcp host.

This patch removes the requirement for a fabric name by making it optional.
Signed-off-by: NBoris Fiuczynski <fiuczy@linux.vnet.ibm.com>

Since the NPIV machine is not easy to get, it's very likely to
introduce regressions when doing changes on the existing code.
This patch dumps part of the sysfs files (the necessary ones)
of fc_host as test input data, to test the related util functions.
It could be extended for more fc_host related testing in future.