scsi: docs: Update outdated link to IBM developerworks

IBM decided to retire a lot of the content that was previously hosted on
"developerworks", and so some of the links we've used for documentation are
now dead or redirect to some general landing page with no correlation to
what the links were meant to provide.

The s390-tools package is meanwhile also hosted on github, so we can link
to the script directly instead of to the archive.

Link: https://lore.kernel.org/r/9ab0341d6ddca46cfc885e4cd9dc38f535969b02.1593780621.git.bblock@linux.ibm.com
Reviewed-by: Julian Wiedmann <jwi@linux.ibm.com>
Reviewed-by: Steffen Maier <maier@linux.ibm.com>
Signed-off-by: Benjamin Block <bblock@linux.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Documentation/scsi/scsi-parameters.rst

@@ -94,7 +94,7 @@ parameters may be changed at runtime by the command
 			(/proc/sys/dev/scsi/logging_level).
 			There is also a nice 'scsi_logging_level' script in the
 			S390-tools package, available for download at
-			http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
+			https://github.com/ibm-s390-tools/s390-tools/blob/master/scripts/scsi_logging_level
 
 	scsi_mod.scan=	[SCSI] sync (default) scans SCSI busses as they are
 			discovered.  async scans them in kernel threads,