MAINTAINERS: update linux-user maintainer

I haven't been active for a while. Pass the maintainer hat
forward to Laurent, who has done a stellar job filling in.

Signed-off-by: Riku Voipio <[email protected]>
Reviewed-by: Philippe Mathieu-Daudé <[email protected]>
Message-Id: <[email protected]>
Signed-off-by: Laurent Vivier <[email protected]>

Author: Riku Voipio

MAINTAINERS

@@ -2629,8 +2629,7 @@ F: bsd-user/
 F: default-configs/*-bsd-user.mak
 
 Linux user
-M: Riku Voipio <[email protected]>
-R: Laurent Vivier <[email protected]>
+M: Laurent Vivier <[email protected]>
 S: Maintained
 F: linux-user/
 F: default-configs/*-linux-user.mak