scsi: cxlflash: Update cxlflash_afu_sync() to return errno

scsi: cxlflash: Update cxlflash_afu_sync() to return errno

BugLink: http://bugs.launchpad.net/bugs/1702521
The cxlflash_afu_sync() routine returns a negative one to indicate any kind
of failure. This makes it impossible to establish why the error occurred.

Update the return codes to clearly indicate the failure cause to the
caller.

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>
(cherry picked from commit 539d890cecee6b5d7304914afc51b7f53150163d)
Signed-off-by: Victor Aoqui <victora@linux.vnet.ibm.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Acked-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>