mailmap: Update email for Sean Nyekjaer

As I'll no longer be working with Prevas, add a mailmap entry so
any mail directed towards me reaches the appropriate mailbox.
Signed-off-by: Sean Nyekjaer <sean@geanix.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

.mailmap

@@ -187,6 +187,7 @@ Santosh Shilimkar <ssantosh@kernel.org>
 Santosh Shilimkar <santosh.shilimkar@oracle.org>
 Sascha Hauer <s.hauer@pengutronix.de>
 S.Çağlar Onur <caglar@pardus.org.tr>
+Sean Nyekjaer <sean@geanix.com> <sean.nyekjaer@prevas.dk>
 Sebastian Reichel <sre@kernel.org> <sre@debian.org>
 Sebastian Reichel <sre@kernel.org> <sebastian.reichel@collabora.co.uk>
 Shiraz Hashim <shiraz.linux.kernel@gmail.com> <shiraz.hashim@st.com>