ARM: dts: msm: Set 320MHz as minimum clock for 8994

The core clock for CPP HW help to determine the vote for CPP.
The minimum clock value of 465MHz results in high vote from
CPP. In order to have optimal tradeoff between bus vote and
CPP HW performance, reduce it to be 320Mhz.

Change-Id: I3b7efe428b82a55d776e61a1bbef56a1c502e427
Signed-off-by: Rajakumar Govindaram <rajakuma@codeaurora.org>