MAINTAINERS: Update AMDGPU DML maintainers info

Chaitanya is no longer with AMD, and the responsibility has been
taken over by Austin.

Signed-off-by: Aurabindo Pillai <[email protected]>
Acked-by: Alex Deucher <[email protected]>
Reviewed-by: Harry Wentland <[email protected]>
Signed-off-by: Alex Deucher <[email protected]>
(cherry picked from commit a101fa7)
Cc: [email protected]

Author: Aurabindo Pillai

MAINTAINERS

@@ -1053,7 +1053,7 @@ T:	git https://gitlab.freedesktop.org/agd5f/linux.git
 F:	drivers/gpu/drm/amd/display/
 
 AMD DISPLAY CORE - DML
-M:	Chaitanya Dhere <chaitanya.dhere@amd.com>
+M:	Austin Zheng <austin.zheng@amd.com>
 M:	Jun Lei <[email protected]>
 S:	Supported
 F:	drivers/gpu/drm/amd/display/dc/dml/