mailmap: add Linus Lüssing

For one thing, summarizes all non-umlaut versions into the umlaut one
(Linus Luessing -> Linus Lüssing).

For another, maps obsolete email addresses to the current @c0d3.blue
one.

Link: http://lkml.kernel.org/r/1467805371-2773-1-git-send-email-linus.luessing@c0d3.blue
Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

.mailmap

@@ -92,6 +92,8 @@ Krzysztof Kozlowski <krzk@kernel.org> <k.kozlowski.k@gmail.com>
 Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
 Leonid I Ananiev <leonid.i.ananiev@intel.com>
 Linas Vepstas <linas@austin.ibm.com>
+Linus Lüssing <linus.luessing@c0d3.blue> <linus.luessing@web.de>
+Linus Lüssing <linus.luessing@c0d3.blue> <linus.luessing@ascom.ch>
 Mark Brown <broonie@sirena.org.uk>
 Matthieu CASTET <castet.matthieu@free.fr>
 Mauro Carvalho Chehab <mchehab@kernel.org> <maurochehab@gmail.com> <mchehab@infradead.org> <mchehab@redhat.com> <m.chehab@samsung.com> <mchehab@osg.samsung.com> <mchehab@s-opensource.com>