dt-bindings: cpufreq: qcom-cpufreq-nvmem: document IPQ8074

Document IPQ8074 compatible for Qcom NVMEM CPUFreq driver.

Signed-off-by: Robert Marko <robimarko@gmail.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>