dt-bindings: arm: qcom,ids: Add SoC IDs for MSM8956 and MSM8976

Document the identifier of MSM8956/76.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20221111120156.48040-7-angelogioacchino.delregno@collabora.com