arm64: dts: qcom: sc7280: remove hbr3 support on herobrine boards

There are some interop issues seen across a few DP monitors with
HBR3 and herobrine boards where the DP display stays blank with hbr3.
This is still under investigation but in preparation for supporting
higher resolutions, its better to disable HBR3 till the issues are
root-caused as there is really no guarantee which monitors will show
the issue and which would not.

This can be enabled back after successful validation across more DP
sinks.

Signed-off-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230329233416.27152-1-quic_abhinavk@quicinc.com