mfd: intel_quark_i2c_gpio: Use dmi_system_id table for retrieving frequency

Avoids reimplementation of DMI matching in intel_quark_i2c_setup.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>