ARM: dts: msm: Set minimum CPUBW based on CPU freq for MSM8937

This allows setting a DDR frequency floor based on CPU frequency is
addition to using the bw_hwmon governor for decide the final CPU BW
vote. Because of how the BW votes are aggregated, if bw_hwmon pick a lower
vote than the floor, the final vote will be the floor value.

Change-Id: I19e601d7be5fda40dc32b6bd758cbcbe20058ce3
Signed-off-by: Hanumath Prasad <hpprasad@codeaurora.org>