mailmap: Add missing email address

I've been using that email address for contributions for a while but it
seems I never added it to mailmap.

Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Reviewed-by: Sui Jingfeng <suijingfeng@loongson.cn>
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Maxime Ripard <mripard@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20230531133724.133872-1-maxime@cerno.tech

.mailmap

@@ -327,6 +327,7 @@ Mauro Carvalho Chehab <mchehab@kernel.org> <m.chehab@samsung.com>
 Mauro Carvalho Chehab <mchehab@kernel.org> <mchehab@s-opensource.com>
 Maxim Mikityanskiy <maxtram95@gmail.com> <maximmi@mellanox.com>
 Maxim Mikityanskiy <maxtram95@gmail.com> <maximmi@nvidia.com>
+Maxime Ripard <mripard@kernel.org> <maxime@cerno.tech>
 Maxime Ripard <mripard@kernel.org> <maxime.ripard@bootlin.com>
 Maxime Ripard <mripard@kernel.org> <maxime.ripard@free-electrons.com>
 Mayuresh Janorkar <mayur@ti.com>