MAINTAINERS: add myself as an OS/2 maintainer

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
(cherry picked from commit 346ec91764)

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

MAINTAINERS

@@ -559,6 +559,7 @@ Windows ICL                             Matthew Oliver
 ADI/Blackfin DSP                        Marc Hoffman
 Sparc                                   Roman Shaposhnik
 x86                                     Michael Niedermayer
+OS/2                                    KO Myung-Hun
 
 
 Releases