drm/vc4: hvs: SCALER_DISPBKGND_AUTOHS is only valid on HVS4

drm/vc4: hvs: SCALER_DISPBKGND_AUTOHS is only valid on HVS4

[ Upstream commit c9df3292709c62091b9ae51204f4b99a5ab1744d ]

The bit used for SCALER_DISPBKGND_AUTOHS in SCALER_DISPBKGNDX
has been repurposed on HVS5 to configure whether a display can
win back-to-back arbitration wins for the COB.

This is not desirable, therefore only select this bit on HVS4,
and explicitly clear it on HVS5.

Fixes: 0d1c2ca1b0b0 ("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-v1-3-1f8e0770798b@cerno.tech
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Signed-off-by: Sasha Levin <sashal@kernel.org>