Add Uwe Kleine-König to .mailmap

There are a few commits that misencoded my name (or used "oe" instead of
"ö").  So add a correct version to .mailmap.
Signed-off-by: Uwe Kleine-König <ukleinek@informatik.uni-freiburg.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

.mailmap

@@ -96,4 +96,6 @@ Tejun Heo <htejun@gmail.com>
 Thomas Graf <tgraf@suug.ch>
 Tony Luck <tony.luck@intel.com>
 Tsuneo Yoshioka <Tsuneo.Yoshioka@f-secure.com>
+Uwe Kleine-König <Uwe.Kleine-Koenig@digi.com>
+Uwe Kleine-König <ukleinek@informatik.uni-freiburg.de>
 Valdis Kletnieks <Valdis.Kletnieks@vt.edu>