Fix _path used by tcm_fc
Fix _path used by tcm_fc

tcm_fc has a different name than the configfs dir it uses. When converting
to classes, we kept setting self.configfs_group but stopped overriding it
for tcm_fc, causing things to break.

Change docs to tell subclasses to override self._path, and fix fcoe class
to match.

Reported-by: Chris Leech <f41d96ff3adb0e2b307a97501bd8a13e9656e292@redhat.com>
Signed-off-by: Andy Grover <b7d524d2f5cc5aebadb6b92b08d3ab26911cde33@redhat.com>

agrover/rtslib-fb,cvubrugier/rtslib-fb,mikenawrocki/rtslib-fb,mikenawrocki/rtslib-fb