scsi: lpfc: Fix pt2pt state transition causing rmmod hang

On a setup with a dual port HBA and both ports direct connected, an rmmod
hangs momentarily when we log an Illegal State Transition. Once it resumes,
a nodelist not empty logic is hit, which forces rmmod to cleanup and exit.
We're missing a state transition case in the discovery engine.

Fix by adding a case for a DEVICE_RM event while in the unmapped state to
avoid illegal state transition log message.

Link: https://lore.kernel.org/r/20210301171821.3427-17-jsmart2021@gmail.com


Co-developed-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <jsmart2021@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>