dt-bindings: cpufreq: Introduce QCOM CPUFREQ Firmware bindings

Add QCOM cpufreq firmware device bindings for Qualcomm Technology Inc's
SoCs. This is required for managing the cpu frequency transitions which are
controlled by the hardware engine.

Change-Id: Ib5eca3981a5dbc0897cf127cda87508145c5d5fb
Signed-off-by: Taniya Das <tdas@codeaurora.org>