i2c: designware: get fast plus and high speed *CNT configuration

I2C designware controller can run at fast mode plus and high speed. This
patch adds the capability to get the HCNT, LCNT configuration via
FPCN (fast plus) and HSCN (high speed) ACPI method.

Signed-off-by: Weifeng Voon <weifeng.voon@intel.com>
Signed-off-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>