dt-bindings: remoteproc: qcom,glink-edge: require channels in children

dt-bindings: remoteproc: qcom,glink-edge: require channels in children

GLINK edge contains subnodes representing devices related to the remote
processor.  Each of such device (e.g. APR or FastRPC) must have
a "qcom,glink-channels" property.  However the APR or FastRPC device can
be also part of other communication - SMD - thus their schema does not
require "qcom,glink-channels".

To make the GLINK edge bindings strict, require "qcom,glink-channels"
for its children.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20220909125403.803158-6-krzysztof.kozlowski@linaro.org
Signed-off-by: Rob Herring <robh@kernel.org>