[SCSI] fcoe: reset FIP ctlr link state on disable/enable

The FIP controler state wasn't being reset on a disable.
A disable/enable sequence should be treated as a link event.
Otherwise, when using disable to mask a time when the link
is up but unusable, FCF discovery would attempt to continue
and login would jump directly to the non-FIP fallback on
enable.

Signed-off-by: Chris Leech <christopher.leech@intel.com>
Signed-off-by: Robert Love <robert.w.love@intel.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>