dt-bindings: soc: qcom: Add remote-pid binding for GLINK SMEM

Add missing qcom,remote-pid dt binding required for GLINK SMEM
which specifies the remote endpoint of the GLINK edge.

Fixes: 2b41d6c8 ("dt-bindings: soc: qcom: Extend GLINK to cover SMEM")
Reviewed-by: Doug Anderson <dianders@chromium.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Sibi Sankar <sibis@codeaurora.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

Documentation/devicetree/bindings/soc/qcom/qcom,glink.txt

@@ -21,6 +21,11 @@ edge.
 	Definition: should specify the IRQ used by the remote processor to
 		    signal this processor about communication related events
 
+- qcom,remote-pid:
+	Usage: required for glink-smem
+	Value type: <u32>
+	Definition: specifies the identifier of the remote endpoint of this edge
+
 - qcom,rpm-msg-ram:
 	Usage: required for glink-rpm
 	Value type: <prop-encoded-array>