arm64: dts: qcom: sc8280xp: Use MMCX for all DP controllers

arm64: dts: qcom: sc8280xp: Use MMCX for all DP controllers

While MDSS_GDSC is a subdomain of MMCX, Linux does not respect this
relationship and sometimes invokes sync_state on the rpmhpd (MMCX)
before the DisplayPort controller has had a chance to probe.

The result when this happens is that the power is lost to the multimedia
subsystem between the probe of msm_drv and the DisplayPort controller -
which results in an irrecoverable state.

While this is an implementation problem, this aligns the power domain
setting of the one DP instance with that of all the others.

Fixes: 57d6ef683a15 ("arm64: dts: qcom: sc8280xp: Define some of the display blocks")
Signed-off-by: Bjorn Andersson <quic_bjorande@quicinc.com>
Reviewed-by: Johan Hovold <johan+linaro@kernel.org>
Reviewed-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230112135055.3836555-1-quic_bjorande@quicinc.com