MAINTAINERS: update media vimc driver maintainers

Based on the dicussion with Hans Verkuil and others in the thread below,
vimc is need of a maintainer. I will start maintaining the driver with
help from Kieran Bingham as the reviewer.

Link: https://lore.kernel.org/linux-media/5d5dee88-9dbf-e4d0-4a91-11ff4ecd82ea@xs4all.nl/Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
Acked-by: Helen Koike <helen@koikeco.de>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>

MAINTAINERS

@@ -20355,8 +20355,8 @@ F:	drivers/media/common/videobuf2/*
 F:	include/media/videobuf2-*
 
 VIMC VIRTUAL MEDIA CONTROLLER DRIVER
-M:	Helen Koike <helen.koike@collabora.com>
-R:	Shuah Khan <skhan@linuxfoundation.org>
+M:	Shuah Khan <skhan@linuxfoundation.org>
+R:	Kieran Bingham <kieran.bingham@ideasonboard.com>
 L:	linux-media@vger.kernel.org
 S:	Maintained
 W:	https://linuxtv.org