regulator: add a regulator driver for the PM8008 PMIC

Qualcomm Technologies, Inc. PM8008 is an I2C controlled PMIC
containing 7 LDO regulators (two N600 and five P300).  Add a
PM8008 regulator driver to support PMIC regulator management
via the regulator framework.

This is a snapshot of the PM8008 regulator driver found in the
msm-4.19 kernel branch with a few small changes.  The most
significant of these was replacing module_platform_driver()
with module_init() and module_exit() to avoid a compilation
error when compiling the driver as a module.

Change-Id: Ie8d96b50558b8dd3084134216dff6393bac16f71
Signed-off-by: Ashay Jaiswal <ashayj@codeaurora.org>
Signed-off-by: Umang Agrawal <uagrawal@codeaurora.org>
Signed-off-by: David Collins <collinsd@codeaurora.org>