abituguru3: update MAINTAINERS

Hans passed maintainership of the abituguru3 hwmon driver onto me.  Add
a new entry to the MAINTAINERS file for the abituguru3 driver and assign
it to me.  Also update the existing UGURU entry to indicate that Hans is
only responsible for the abituguru driver.

Signed-off-by: Alistair John Strachan <alistair@devzero.co.uk>
Acked-by: Hans de Goede <j.w.r.degoede@hhs.nl>
Cc: Jean Delvare <khali@linux-fr.org>
Cc: "Mark M. Hoffman" <mhoffman@lightlink.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>