dt-bindings: remoteproc: k3-dsp: Cleanup SoC compatible from DT example

dt-bindings: remoteproc: k3-dsp: Cleanup SoC compatible from DT example

The K3 DSP binding example used the root-node with a SoC compatible
property originally to address the dt_binding_check warnings resulting
from using a value of 2 for #address-cells and #size-cells as per most
common usage on K3 SoCs. Clean this up and replace it with a generic soc
node to keep it agnostic of the SoC or board compatibles that are outside
the scope of this binding.

Signed-off-by: Sinthu Raja <sinthu.raja@ti.com>
Acked-by: Rob Herring <robh@kernel.org>
Acked-by: Suman Anna <s-anna@ti.com>
Reviewed-by: Nishanth Menon <nm@ti.com>
Link: https://lore.kernel.org/r/20210927103811.11222-3-sinthu.raja@ti.com
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>