ARM: dts: msm: Update CPU clock min frequncy for MSM8937

MSM8937 CPU minimum frequency is updated to support 960MHz and 768MHz
respectively for big and little cluster , so update the frequency table
and the CPR node to reflect the same.

Change-Id: I32bfa8e2360befb3a4c1dde081afb49fe9e392d4
Signed-off-by: Odelu Kukatla <okukatla@codeaurora.org>