Left dmesg debug logging in the DSACK code.
As the DSACK functionality was thoroughly debugged in the
meantime, this is no longer necessary.
DSACK timeline and required patches so far:
rS347382 (2019-05-09) - initial dirty hack
rS349987 (2019-07-14) - send dsack blk only once
rS351725 (2019-09-02) - fully conform with rfc2883
rS351801 (2019-09-02) - fix SACK block generation
rS352072 (2019-09-02) - update dsack only for data segments
rS352386 (2019-09-16) - fix out of bounds write
rS356796 (2020-01-16) - remove debug code