[SCSI] lpfc 8.3.7: Fix discovery failures.

Fix discovery failures:
- Move all accesses to the fc_flag field inside the host lock.
- Restore link state after going through linkdown processing for FCF DEAD event.

Signed-off-by: James Smart <james.smart@emulex.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>