MAINTAINERS: add Simon as an official reviewer

Simon has been diligently and consistently reviewing networking
changes for at least as long as our development statistics
go back. Often if not usually topping the list of reviewers.
Make his role official.

Acked-by: Eric Dumazet <[email protected]>
Acked-by: Paolo Abeni <[email protected]>
Signed-off-by: Jakub Kicinski <[email protected]>
Reviewed-by: Simon Horman <[email protected]>
Message-ID: <[email protected]>
Signed-off-by: Andrew Lunn <[email protected]>

Author: kuba-moo

MAINTAINERS

@@ -16152,6 +16152,7 @@ M:	"David S. Miller" <[email protected]>
 M:	Eric Dumazet <[email protected]>
 M:	Jakub Kicinski <[email protected]>
 M:	Paolo Abeni <[email protected]>
+R:	Simon Horman <[email protected]>
 L:	[email protected]
 S:	Maintained
 P:	Documentation/process/maintainer-netdev.rst