v4l2: camera_proxy: Fix header include order

The includes in the v4l2_camera_proxy do not match the code style
and trigger clang-format changes when running checkstyle.

Update and fix the include order accordingly

Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Umang Jain <umang.jain@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>