mailmap: add entries for Heiko Stuebner

I am going to lose my vrull.eu address at the end of july, and while
adding it to mailmap I also realised that there are more old addresses
from me dangling, so update .mailmap for all of them.

Link: https://lkml.kernel.org/r/20230704163919.1136784-3-heiko@sntech.de
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Heiko Stuebner <heiko.stuebner@vrull.eu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

.mailmap

@@ -178,6 +178,9 @@ Gustavo Padovan <padovan@profusion.mobi>
 Hanjun Guo <guohanjun@huawei.com> <hanjun.guo@linaro.org>
 Heiko Carstens <hca@linux.ibm.com> <h.carstens@de.ibm.com>
 Heiko Carstens <hca@linux.ibm.com> <heiko.carstens@de.ibm.com>
+Heiko Stuebner <heiko@sntech.de> <heiko.stuebner@bqreaders.com>
+Heiko Stuebner <heiko@sntech.de> <heiko.stuebner@theobroma-systems.com>
+Heiko Stuebner <heiko@sntech.de> <heiko.stuebner@vrull.eu>
 Henk Vergonet <Henk.Vergonet@gmail.com>
 Henrik Kretzschmar <henne@nachtwindheim.de>
 Henrik Rydberg <rydberg@bitmath.org>