ARM: dts: msm: Move Power@800MHz and Perf@960MHz to Nominal

The latest 8939 clock plan incorporated below changes:
 1. Power cluster Nominal Fmax to 800MHz.
 2. Performance cluster Nominal Fmax to 960MHz.

Updated the corresponding virtual corner and CCI mappings.

CRs-Fixed: 709707
Change-Id: I1ecc33e35c5a3236d12085cfcb84be2294800fe0
Signed-off-by: Tirupathi Reddy <tirupath@codeaurora.org>