clk: msm: clock-cpu-8996: Reduce the alt PLL's early boot frequency

The alt PLL may be used even in the absence of CPR
safe mode or clock throttling. Comfigure it to a
safe frequency for the power and perf clusters at
bootup.

Change-Id: Ic9596b038b9ef8ac35379da52729c58f73884223
Signed-off-by: Vikram Mulukutla <markivx@codeaurora.org>