ARM: dts: msm8974: Move ADSP smd edge to ADSP PIL

With the introduction of SSR support in the ADSP PIL we should describe
the SMD edge inside the ADSP PIL node.

Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
[luca@z3ntu.xyz: Add label for the smd edge]
Signed-off-by: Luca Weiss <luca@z3ntu.xyz>
Link: https://lore.kernel.org/r/20191114175348.288976-2-luca@z3ntu.xyz


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