MAINTAINERS: delete email for Anton Sviridenko

The email address bounced. I couldn't find a newer one in recent git
history, so update MAINTAINERS accordingly.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>