msm: acpuclock-krait: Initial commit with msm-copper support

Add a new generic acpuclock driver for Krait CPUs, along with msm-copper
specific configuration data. This is a generalization of the existing
acpuclock-8960 driver, which it is intended to eventually replace. A
library of core driver code exists in acpuclock-krait.c with target-
specific data living in acpuclock-copper.c (and, eventually, other
similarly-named files).

Unlike existing acpuclock drivers, acpuclock-copper is a platform driver
with a platform device defined in a device tree. The driver probes when
the platform device has been registered and platform_driver_probe() has
been called in acpuclock-copper's device initcall.

Change-Id: I334ed0e215bb4076461f7bc39cf4ec89dbc35a8e
Signed-off-by: Matt Wagantall <mattw@codeaurora.org>