clk: msm: clock-cpu-8996: Modify OPP population

Populate only the rates in the fmax array (that is read
from DT) in the OPP tables for each clock. Also, move
OPP population earlier, since the CPU devices are now
available earlier in the boot process.

Change-Id: I6d860c549b02d458c8fe815b95ac08bd6f823442
Signed-off-by: Vikram Mulukutla <markivx@codeaurora.org>