scsi: ibmvfc: Avoid path failures during live migration

scsi: ibmvfc: Avoid path failures during live migration

Fix an issue reported when performing a live migration when multipath is
configured with a short fast fail timeout of 5 seconds and also to have
no_path_retry set to fail. In this scenario, all paths would go into the
devloss state while the ibmvfc driver went through discovery to log back
in. On a loaded system, the discovery might take longer than 5 seconds,
which was resulting in all paths being marked failed, which then resulted
in a read only filesystem.

This patch changes the migration code in ibmvfc to avoid deleting rports at
all in this scenario, so we avoid losing all paths.

Signed-off-by: Brian King <brking@linux.vnet.ibm.com>
Link: https://lore.kernel.org/r/20221026181356.148517-1-brking@linux.vnet.ibm.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>