When doing multipathed Fibre Channel we may end up not flushing the
volume when disconnecting it if didn't find a multipath when doing
the connection.
The issue is caused by the `connect_volume` call returning a real path
instead of a symlink and us passing the wrong device_info to the
_remove_devices method, which makes the disconnect code incorrectly
identify when a multipath was used to decide whether to do a flush or
not.
This patch fixes these things in order to flush the individual path when
necessary.
Closes-Bug: #1897787
Change-Id: Ie3266c81b3c6bb5a2c213a12410539d404d1febe