Now that our usage of C compatibility header is documented, use them
consistently through the source code.
While at it, group the C and C++ include statements as defined in the
coding style, and fix a handful of #include ordering issues.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>