scsi: cxlflash: Introduce object handle fop

OCXL requires that AFUs use an opaque object handle to represent an AFU
interrupt. The specification does not provide a common means to communicate
the object handle to the AFU - each AFU must define this within the AFU
specification. To support this model, the object handle must be passed back to
the core driver as it manages the AFU specification (SISLite) for cxlflash.
Note that for Power systems, the object handle is the effective address of the
trigger page.

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>