arm64: dts: qcom: sdm845: Drop standalone smem node

Now that the SMEM binding and driver allows the SMEM node to be
described in the reserved-memory region directly, move the compatible
and hwlock properties to the reserved-memory node and drop the
standadlone node.

Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Reviewed-by: Vladimir Zapolskiy <vladimir.zapolskiy@linaro.org>
Link: https://lore.kernel.org/r/20210930182111.57353-5-bjorn.andersson@linaro.org