Update postfix-sasl.conf: Different log output on centos.

In our logfile in some cases the message is "...SASL login..." instead of "...SASL LOGIN...".
Maybe it makes sense to change the whole "SASL (?:LOGIN|login|PLAIN|(?:CRAM|DIGEST)-MD5)" block to "SASL.*", because when browsing through the internet I have seen other possibilities then "CRAM,DIGEST,..." but I'm not sure how strict the regex should be handled.
Running Centos 6 - happens only sometimes and only if the domainname to the ip is unknown for postfix.
no need to uppercase ```FAILREGEX```, and if it is just a matter of a lower case ```login``` why just not to add it to the list instead of replacing with a more aggressive ```\S+```

also we would need a sample line into fail2ban/tests/files/logs/postfix-sasl