MAINTAINERS: Add Haihao Xiang for vaapi

Current listed maintainers for vaapi plugin are
not reponsive and/or currently active in the
ffmpeg community.  Thus, vaapi plugin patches
(and qsv plugin) have generally gone ignored or
lost in the ether for too long.

Remove Gwenole Beauchesne from vaapi maintainer
who has not been active since 2016.

Current alternative maintainer for vaapi is Mark
Thompson whom has not been active since
March/April 2021.

Therefore, add Haihao Xiang to vaapi maintainer
who's primary role is FFmpeg development with a
focus on the vaapi and qsv plugins.  Haihao has
over a decade of media experience and many years
of FFmpeg development experience, amongst other
media frameworks.

The additional patch for adding Haihao as qsv
plugin maintainer has been submitted previously:

https://patchwork.ffmpeg.org/project/ffmpeg/patch/[email protected]/

This will help FFmpeg to continue to be the leading
multimedia framework by allowing these plugins to be
actively improved, enhanced, and maintained for existing
and future HW platforms.

Signed-off-by: U. Artie Eoff <[email protected]>

MAINTAINERS

@@ -274,8 +274,8 @@ Hardware acceleration:
   dxva2*                                Hendrik Leppkes, Laurent Aimar, Steve Lhomme
   d3d11va*                              Steve Lhomme
   mediacodec*                           Matthieu Bouron, Aman Gupta
-  vaapi*                                Gwenole Beauchesne
-  vaapi_encode*                         Mark Thompson
+  vaapi*                                Haihao Xiang
+  vaapi_encode*                         Mark Thompson, Haihao Xiang
   vdpau*                                Philip Langdale, Carl Eugen Hoyos
   videotoolbox*                         Rick Kern, Aman Gupta