MAINTAINERS: Change maintainer for hisilicon DRM driver

Remove Rongrong Zou and change tiantao as hisilicon DRM maintainer.

Signed-off-by: Tian Tao <tiantao6@hisilicon.com>
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: xinliang.liu <xinliang.liu@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/1597134186-58423-1-git-send-email-tiantao6@hisilicon.com

MAINTAINERS

@@ -5694,7 +5694,7 @@ F:	drivers/gpu/drm/gma500/
 DRM DRIVERS FOR HISILICON
 M:	Xinliang Liu <xinliang.liu@linaro.org>
-M:	Rongrong Zou <zourongrong@gmail.com>
+M:	Tian Tao  <tiantao6@hisilicon.com>
 R:	John Stultz <john.stultz@linaro.org>
 R:	Xinwei Kong <kong.kongxinwei@hisilicon.com>
 R:	Chen Feng <puck.chen@hisilicon.com>