drm: Use new DRM_BUS_FLAG_*_(DRIVE|SAMPLE)_(POS|NEG)EDGE flags

The DRM_BUS_FLAG_PIXDATA_(POS|NEG)EDGE and
DRM_BUS_FLAG_SYNC_(POS|NEG)EDGE flags are deprecated in favour of the
new DRM_BUS_FLAG_PIXDATA_(DRIVE|SAMPLE)_(POS|NEG)EDGE and
new DRM_BUS_FLAG_SYNC_(DRIVE|SAMPLE)_(POS|NEG)EDGE flags. Replace them
through the code.

This effectively changes the value of the .sampling_edge bridge timings
field in the dumb-vga-dac driver. This is safe to do as no driver
consumes these values yet.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Stefan Agner <stefan@agner.ch>
Tested-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>