.mailmap: add an alias for Lionel Landwerlin

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/1999>
diff --git a/.mailmap b/.mailmap
index b16a821..86d4c37 100644
--- a/.mailmap
+++ b/.mailmap
@@ -364,6 +364,8 @@
 
 Li Peng <peng.li@intel.com> <peng.li@linux.intel.com>
 
+Lionel Landwerlin <lionel.g.landwerlin@intel.com> <llandwerlin@gmail.com>
+
 Lucas Stach <dev@lynxeye.de> <l.stach@pengutronix.de>
 
 Maarten Lankhorst <maarten.lankhorst@ubuntu.com> <dev@mblankhorst.nl>