scsi: target: iscsi: Control authentication per ACL

Add acls/{ACL}/attrib/authentication attribute that controls authentication
for particular ACL. By default, this attribute inherits a value of the
authentication attribute of the target port group to keep backward
compatibility.

Authentication attribute has 3 states:

 "0" - authentication is turned off for this ACL

 "1" - authentication is required for this ACL

 "-1" - authentication is inherited from TPG

Link: https://lore.kernel.org/r/20220523095905.26070-4-d.bogdanov@yadro.com


Reviewed-by: Roman Bolshakov <r.bolshakov@yadro.com>
Reviewed-by: Konstantin Shelekhin <k.shelekhin@yadro.com>
Reviewed-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Dmitry Bogdanov <d.bogdanov@yadro.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>