scsi: cxlflash: Handle AFU sync failures

AFU sync operations are not currently evaluated for failure. This is
acceptable for paths where there is not a dependency on the AFU being
consistent with the host. Examples include link reset events and LUN
cleanup operations. On paths where there is a dependency, such as a LUN
open, a sync failure should be acted upon.

In the event of AFU sync failures, either log or cleanup as appropriate for
operations that are dependent on a successful sync completion.

Update documentation to reflect behavior in the event of an AFU sync
failure.

Signed-off-by: Uma Krishnan <ukrishn@linux.vnet.ibm.com>
Acked-by: Matthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>