MAINTAINERS: arch/nios2: Add Simon Schuster as co-maintainer

Add Simon Schuster as a co-maintainer for the nios2 architecture and
mark it as supported.

Signed-off-by: Simon Schuster <schuster.simon@siemens-energy.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Dinh Nguyen <dinguyen@kernel.org>

Author: Simon Schuster

MAINTAINERS

@@ -18898,7 +18898,8 @@ F:	drivers/hid/hid-nintendo*
 
 NIOS2 ARCHITECTURE
 M:	Dinh Nguyen <dinguyen@kernel.org>
-S:	Maintained
+M:	Simon Schuster <schuster.simon@siemens-energy.com>
+S:	Supported
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/dinguyen/linux.git
 F:	arch/nios2/