MAINTAINERS: add Mattijs for Android AVB

Igor has not been active for quite some time on lore:
https://lore.kernel.org/all/?q=igor.opaniuk@gmail.com



I'm interested in helping with maintaining the android_avb
command. I'm a long time android/aosp developer and my daily job is
still doing android work.

Add myself as maintainer for Android AVB.

Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Reviewed-by: Igor Opaniuk <igor.opaniuk@foundries.io>
Acked-by: Igor Opaniuk <igor.opaniuk@foundries.io>
Reviewed-by: Sam Protsenko <semen.protsenko@linaro.org>
Link: https://lore.kernel.org/r/20240112-maintainers-ab-v1-2-f2a538eab18a@baylibre.com


Signed-off-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>