drm/vc4: hvs: Fix colour order for xRGB1555 on HVS5

[ Upstream commit 902973dc ]

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: Dave Stevenson <dave.stevenson@raspberrypi.com>
Link: https://lore.kernel.org/r/20221207-rpi-hvs-crtc-misc-v1-6-1f8e0770798b@cerno.tech


Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Signed-off-by: Sasha Levin <sashal@kernel.org>