arm64: dts: qcom: apq8096-db820c: enable MSS node

APQ8096 provides a 'modem' with reduced functionality, mainly targeting
location services. Enable corresponding device tree node.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20220403193911.1393920-3-dmitry.baryshkov@linaro.org