MAINTAINERS: Remove me from amdgpu maintainers

Glad to spend time on kernel driver in past years.
I've moved to new focus in umd and couldn't commit
enough time to discussions.
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Chunming Zhou <david1.zhou@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

MAINTAINERS

@@ -13952,7 +13952,6 @@ F:	drivers/net/wireless/quantenna
 RADEON and AMDGPU DRM DRIVERS
 M:	Alex Deucher <alexander.deucher@amd.com>
 M:	Christian König <christian.koenig@amd.com>
-M:	David (ChunMing) Zhou <David1.Zhou@amd.com>
 L:	amd-gfx@lists.freedesktop.org
 T:	git git://people.freedesktop.org/~agd5f/linux
 S:	Supported