mfd: intel_quark_i2c_gpio: support devices behind i2c bus

On Intel Galileo Gen2 the GPIO expanders are connected to the i2c bus. For
those devices the ACPI table has specific parameters that refer to an actual
i2c host controller. Since MFD now copes with that specific configuration we
have to provide a necessary information how to distinguish devices in ACPI
namespace. Here the _ADR values are provided.

Acked-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>