arm64: dts: qcom: sm8250: rename smem device node to follow schema

Rename 'qcom,smem' to just 'smem' to follow the rest of SoC (and device
schema).

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://lore.kernel.org/r/20201203191335.927001-2-dmitry.baryshkov@linaro.org


Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>