Same as the xRGB8888 formats, HVS5 has managed to swap the colour
channels for the xRGB1555 formats as well. Add the relevant
config for pixel_order_hvs5.

Fixes: c54619b0 ("drm/vc4: Add support for the BCM2711 HVS5")
Signed-off-by: NDave Stevenson <dave.stevenson@raspberrypi.com>
Link: https://lore.kernel.org/r/20221207-rpi-hvs-crtc-misc-v1-6-1f8e0770798b@cerno.techSigned-off-by: NMaxime Ripard <maxime@cerno.tech>