MAINTAINERS: Update email of Neil Armstrong

My professional e-mail will change and the BayLibre one will
bounce after mid-september of 2022.

This updates the MAINTAINERS files and adds an entry in the
.mailmap file.

Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
diff --git a/.mailmap b/.mailmap
index f27f366..8acce4b 100644
--- a/.mailmap
+++ b/.mailmap
@@ -49,6 +49,7 @@
 Michal Simek <michal.simek@xilinx.com> <monstr@monstr.eu>
 Michal Simek <michal.simek@xilinx.com> <Monstr@seznam.cz>
 Michal Simek <michal.simek@xilinx.com> <root@monstr.eu>
+Neil Armstrong <neil.armstrong@linaro.org> <narmstrong@baylibre.com>
 Nicolas Saenz Julienne <nsaenz@kernel.org> <nsaenzjulienne@suse.de>
 Patrice Chotard <patrice.chotard@foss.st.com> <patrice.chotard@st.com>
 Patrick Delaunay <patrick.delaunay@foss.st.com> <patrick.delaunay@st.com>