platform-drivers: msm: add single-wire serial bus interface (SSBI) driver

SSBI is the Qualcomm single-wire serial bus interface used to connect
the MSM devices to the PMIC and other devices.

Since SSBI only supports a single slave, the driver gets the name of the
slave device passed in from the board file through the master device's
platform data.

SSBI registers pretty early (postcore), so that the PMIC can come up
before the board init. This is useful if the board init requires the
use of gpios that are connected through the PMIC.

Based on a patch by Dima Zavin <dima@android.com> that can be found at:
http://android.git.kernel.org/?p=kernel/msm.git;a=commitdiff;h=eb060bac4



This patch adds PMIC Arbiter support for the MSM8660. The PMIC Arbiter
is a hardware wrapper around the SSBI 2.0 controller that is designed to
overcome concurrency issues and security limitations.  A controller_type
field is added to the platform data to specify the type of the SSBI
controller (1.0, 2.0, or PMIC Arbiter).

Change-Id: Ic37e1505f0ed7cfb8c5926a4c8d1770aa43e67cc
Signed-off-by: Kenneth Heitke <kheitke@codeaurora.org>