power: Rename power-8952.c to power-8937.c

* Latest power-8952.c is used for msm8937 with mpctl V3.
  Rename the file so we can add back the legacy msm8952 handling.

Change-Id: Iccd2a3c0abed2ef10d5f6c2182c0509a2fbe611d
2 files changed