dt-bindings: soc: qcom: qcom,smd-rpm: Use qcom,smd-channels on MSM8976

Like MSM8916 and some others, MSM8976 uses qcom,smd-channels and not
qcom,glink-channels.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20221104172122.252761-5-angelogioacchino.delregno@collabora.com