toradex: take over maintainership

Also take over maintainership of remaining Toradex SoMs as Oleksandr
has left our company.

Signed-off-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
CC: Oleksandr Suvorov <cryosay@gmail.com>
diff --git a/board/toradex/colibri_t20/MAINTAINERS b/board/toradex/colibri_t20/MAINTAINERS
index 61fbd2c..77c2fc3 100644
--- a/board/toradex/colibri_t20/MAINTAINERS
+++ b/board/toradex/colibri_t20/MAINTAINERS
@@ -1,5 +1,5 @@
 COLIBRI_T20
-M:	Oleksandr Suvorov <oleksandr.suvorov@toradex.com>
+M:	Marcel Ziswiler <marcel.ziswiler@toradex.com>
 S:	Maintained
 F:	board/toradex/colibri_t20/
 F:	include/configs/colibri_t20.h