MAINTAINERS: update s390/net

Remove Thorsten Winkler as maintainer and add Aswin Karuvally as reviewer.

Thank you Thorsten for your support, welcome Aswin!

Signed-off-by: Alexandra Winter <[email protected]>
Acked-by: Thorsten Winkler <[email protected]>
Acked-by: Aswin Karuvally <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: SandyWinter

MAINTAINERS

@@ -22174,7 +22174,7 @@ F:	arch/s390/mm
 
 S390 NETWORK DRIVERS
 M:	Alexandra Winter <[email protected]>
-M:	Thorsten Winkler <twinkler@linux.ibm.com>
+R:	Aswin Karuvally <aswin@linux.ibm.com>
 L:	[email protected]
 L:	[email protected]
 S:	Supported