scsi: scsi_dh_alua: Increase default ALUA timeout to maximum spec value

scsi: scsi_dh_alua: Increase default ALUA timeout to maximum spec value

The ALUA handler maps a 0 value (no implicit transition timeout provided
by the target) to the ALUA_FAILOVER_TIMEOUT constant, currently 60
seconds. This means the kernel already does not accept an infinite
transition time.

However, 60 seconds is insufficient for some arrays that may take longer
to complete ALUA transitions. Since the highest value allowed by the
SCSI specification for the implicit transition timeout is a single byte
(255 seconds), change the default to 255. This way, when a target does
not provide an explicit transition timeout, we default to the maximum
value the spec allows rather than an arbitrary 60 second limit.

Co-developed-by: Krishna Kant <krishna.kant@purestorage.com>
Signed-off-by: Krishna Kant <krishna.kant@purestorage.com>
Co-developed-by: Riya Savla <rsavla@purestorage.com>
Signed-off-by: Riya Savla <rsavla@purestorage.com>
Signed-off-by: Brian Bunker <brian@purestorage.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Link: https://patch.msgid.link/20260416165512.26497-2-brian@purestorage.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>