.mailmap: add an alias for Dave Airlie

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/1999>
diff --git a/.mailmap b/.mailmap
index 69950fb..873ea04 100644
--- a/.mailmap
+++ b/.mailmap
@@ -11,6 +11,7 @@
 Dave Airlie <airlied@redhat.com> <airliedfreedesktop.org>
 Dave Airlie <airlied@redhat.com> airlied <airlied@unused-12-215.bne.redhat.com>
 Dave Airlie <airlied@redhat.com> <airlied@dhcp-1-203.bne.redhat.com>
+Dave Airlie <airlied@redhat.com> <airlied@dhcp-40-204.bne.redhat.com>
 Dave Airlie <airlied@redhat.com> <airlied@gmail.com>
 Dave Airlie <airlied@redhat.com> <airlied@itt42.(none)>
 Dave Airlie <airlied@redhat.com> <airlied@linux.ie>