MAINTAINERS: Update maintainers/reviewers for bridge drivers

MAINTAINERS: Update maintainers/reviewers for bridge drivers

Add Laurent as a reviewer and Andrzej as a maintainer for DRM bridge chip
drivers. They actively review and contribute to bridge drivers and the
bridge API.

Acked-by: Andrzej Hajda <a.hajda@samsung.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Archit Taneja <architt@codeaurora.org>
Link: http://patchwork.freedesktop.org/patch/msgid/20170410063641.17704-1-architt@codeaurora.org