arm64: dts: qcom: sdm845: Define the number of available ports

The number of available ports is SoC specific so we should define it in the
SoC dtsi. For the case of the sdm845 that is 4 CSI PHYs => four ports.

Reviewed-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20221117003232.589734-2-bryan.odonoghue@linaro.org