linux-phytec-ti

MAINTAINERS: Updated information for DRBD DRIVER

- Changed obsoleted 'P' to 'M' entries.
- Removed the user related mailing list.
- Changed git repos to current versions

Signed-off-by: Roland Kammerer <roland.kammerer@linbit.com>
Signed-off-by: Jens Axboe <axboe@fb.com>