i2c-cht-wc: Add Intel Cherry Trail Whiskey Cove SMBUS controller driver

The Intel Cherry Trail Whiskey Cove PMIC does not contain a builtin
battery charger, instead boards with this PMIC use an external TI
bq24292i charger IC, which is connected to a SMBUS controller built into
the PMIC.

This commit adds an i2c-bus driver for the PMIC's builtin SMBUS
controller. The probe function for this i2c-bus will also register an
i2c-client for the TI bq24292i charger after the i2c-bus has been
registered.

Note that several device-properties are set on the client-device to
tell the bq24190 power-supply driver to integrate the Whiskey Cove PMIC
and e.g. use the PMIC's BC1.2 detection (through extcon) to determine
the maximum input current.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>