scsi: core: Introduce scsi_cmd_list_info()

Slightly improve code readability by introducing a helper function for
deriving the list information and by using guard() + return instead of
goto + explicit unlock + return.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20240325224755.1477910-2-bvanassche@acm.org


Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>