mailmap: add Martin Kepplinger's email

Set the partly deprecated companies' email addresses as alias for the
personal one.

Link: http://lkml.kernel.org/r/1491984622-17321-1-git-send-email-martin.kepplinger@ginzinger.com


Signed-off-by: Martin Kepplinger <martin.kepplinger@ginzinger.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>